Music and Acoustics with Greg Bryant
2026-03-24 12:00:00.000 +00:00

This is Evolutionary Psychology of the Podcast. I'm David Petrozowski. And I'm David Pinsov. This is actual evolutionary psychology by actual Evolutionary Psychologist. David, did you hear that? What what? I I Oh well uh the nothing in particular. I was just wondering because what who we're talking to today is Greg Bryant, and Greg Bryant does all things acoustic. That's right. Uh we get into vocal communication, music, uh why different sounds evoke different emotions in us, whether those connections between sounds and emotions are arbitrary, or whether they have sort of interesting evolutionary explanations. Yeah, I think I think for me the mystery of why music makes us feel anything is was partially resolved by this.

And I feel like Greg did an amazing job um organizing my thinking. And I knew about Greg's work. Um, but even this conversation for me really helped organize my thinking. Um, for example, understanding, yeah, like what's up with music, why do we feel emotions around that? Um, why is rock music the way it is? Um, and how is it related to yeah, um you will learn why electric guitars are distorted and what role that distortion is playing. Yeah the evolutionary psychology of uh overdrive is should be the title of of this episode maybe um uh yeah and then we also talk about Greg's other work. We spent a lot of time on music which is fantastic. Um but we also do talk about um some of his other work about and we get toward the end we

talk about humor and laughter. Oh yeah, I talked a lot about laughter and um uh how it ties in with encryption theory and with my own work on uh mix-ups. Uh it was a really fun conversation and I learned a lot and had a great time. Yeah, so uh this is in acoustic format. So sit back, enjoy and listen. And yeah, I've I you'll learn a lot and uh maybe think about what you're doing with your ears slightly differently after you do the following with your ears, which is a weird way to say that, but I guess I'll enjoy listening to a podcast about sound with your ears. We usually do just you know like an introduction before your own, so we'll just get right into it. Um if evolutionary behavioral sciences were a heist movie, um, you would be the acoustic

expert, is sort of my representation of you. Um uh have you always been an audiophile? Yeah, well, I mean it's funny you use the term audiophile because that is has a specific meaning, um, meaning that it's people that are into super high-end gear, and there's actually can be almost a religious element where you think there are differences in sound between the tube amp with the shielded cables, the whatever. Yeah, Versus a solid state modeling app that sounds exactly the same. And yeah. That's the thing. So I usually land on that side of the debate because I'm a perceptual psychologist, yeah. Um, but I am I mean I am an audiophile and that's I was raised by audiophiles. My dad was was into stereos and he was a um actually in the sound um

in the army corps with uh the uh the uh radio corps, sorry. Nice army. So he was interested in that kind of stuff, and so we always had nice stereos, and my dad was really into music, and my brother got into that that way, and then he does is he's a software engineer who works on audio compression, so it's a sound situation in my family, so I guess that's where I get it. And then I was obviously very into music from a young age, And so yeah, I've always kind of been into sound. And that was sort of my attraction to um evolution and behavior was the connection between language and music and trying to think about, you know, speech communication and vocal communication in general. Yeah, that's awesome.

I mean, uh, learn versus innate is a dumb distinction, but I mean it captures something in w looking at your family and being like, wow, we're really all into music, have you thought about, you know, like is it is it that because it was all around? Or or what's your take on those? Yeah. Yeah, that I mean that probably that must have played some role, right? I mean, it's hard to say, though it's funny though, the music thing is they're into music listening, but not into music performance. So I had to beg my parents to give me any kind of musical instrument. And I didn't really get one until I was about fifteen years old. I got an electric guitar, which I'm and at the time they were probably like, this is why we

didn't want to do this. Because you were like distortion. What was it? It was a Hondo strat copy, and then a Sun 20-watt amp, which that I wish I still had that thing because Sun is a really cool make and they had a really distortion built in. But I was into like speed metal and punk rock. I mean, it was probably a nightmare for them. Um, but I mean, I would have played piano if I had one and I wanted a guitar when I was eight years old. I actually asked first for a guitar and they just wouldn't give me an instrument because I think they you know they had the classic, you know, you're we're gonna buy it for you and then it's just gonna sit around. And they didn't believe that I was really into it, and I was.

Right. So in that sense, they've they hindered my music development. I'm sorry. Yeah. I probably would, you know, I would have different skills if I had learned m instruments when I was eight, you know. Yeah. Like I mean, in in some ways, maybe it would be better. I mean, I don't read music. Um, I understand music theory uh you know conceptually, but I can't sight read. And so if I look at some sheet music, I can't play it on the guitar. Without meaning it would be a lot of work for me to figure that out. Um and so that gives you different skills. Like, for example, I might have developed perfect pitch if I had learned the notes and the theory and the instrument when I was young. And now I'll never learn I'll never have perfect pitch.

Once you're an adult, the evidence is pretty good. Once you pass that threshold, you never get perfect pitch. So I have good relative pitch. Um, but yeah, so there's these certain little skills that you get when you learn early that are just obtainable later. So yeah, it was kind of an interesting combination. They were really into the listening, but not the playing. Interesting. Yeah. Well, this is a PSA. Sorry, David. PSA. If your kid wants to play music, uh my editorial here is let them. And if they don't use it, you can always put the thing on reverb and get a good reset. Yeah, let them if they want to, but don't push it on them either. No, yes, exactly. I know so many people that were forced to take piano lessons that now have like an

aversion, they don't even want to do anything. Totally, David. Yeah, really good. Exactly. Just like horror. It's it's it's you let them be autonomous and let the and let them let them do overdrive. You can give them uh headphones and stuff. Uh Greg, can you talk about perfect pitch? Cause that's like maybe a nice little hook into content. Um because uh you know I've been reading into this too. I came across this because I had always had this toy idea that perfect pitch was just something people are born with or not. Um for people who don't know what it is, can you explain what it is and then can you tell us if to extent you know I mean I'm I know this is not your primary research, but like what

is the state of the art that we know about it? Yeah. Well, uh the idea of perfect pitch, my understanding, is that when um a person can map a tone onto a note. So if you hear, you know, a tone of whatever it might be, you can just say that's an A. That's right. And you if you say like do an A, they can hum it or uh Exactly. So they um and they nail it right exactly. Yeah, yeah. And so that's something that you learn that mapping between the sound and the category early. And um because obviously the category is culturally constrained. There's no way it could be an A to know an A because A is a cultural invention. Yeah, right, exactly. In German it's like there's another different note. I know Annie always talks about that.

It's like it's a it's it's like a different there's like an H or something. I I forget the DS. I'm I'm completely a musical, so I'm is it the fun note, the huh? Yeah, that's exactly it's right. Yeah, good and talk to all of our German uh friends. So yeah. Yeah. So obviously, you know, you have to learn some system, and there's a lot of them out there, potentially. Um, so if it's learned within a critical period, which I think is it's right in the language critical period. So it's kind of like before your five. And people a lot of people say, I had perfect pitch and I never had music lessons. It's like, except that one time, you know, that it always, if you push them, it always, oh, there was one little thing.

It doesn't take much, I think. You know, kids soak it up pretty fast. Um, once you pass that threshold, I think the evidence is that that you can't learn it. So you have to have some sort of relative pitch to the know you know the difference between it and so you have a reference pitch, then you can say what the note is if you're really good at it. You can learn that. And and can I just interrupt? Is it that because I mean, so you know, I I know somebody with perfect pitch, like it's when you when they play a note or you do a note, it's it's it would be like asking the most people like what color is this? It's like, oh my gosh, of course it's red, right? It's like it's boring, and I'm just like, I don't I don't know how you do that.

Um, is it that the lessons create the discrete mappings between the notes? Or is it just that you need a linguistic um label, but the shelf, the cognitive shelf for that um note is already there, if that makes sense. Or if that I don't know if I'm making the uh well, I mean the instruments produce there's not a lot of variation. So I mean if they learned with a bad piano, for example, then that would probably screw the mechanism up. Okay. Um, because then people later would say they'd play A440 and then they learned it like A452. Oh, I think that's then they'd they would that might. I mean, I'd that would be kind of a bad experiment to do to do that. But um, but I think that could mess it up.

So the thing is that people are learning with instruments that are tuned properly, you know, to like a regular piano that's tuned reasonably. But I mean there's probably some error in there. I see. So it's the intervals. They're actually learning the the the fundamental frequency intervals, or like what counts as a step in in a continuous range of frequencies. They do, except actually you learn it without reference pitch. So you add a context, just one note, you can do it. So that means you it's not necessarily about an interval because the interval is two or more notes. Oh, I see. I was using the wrong term. I just meant a space. Sorry. I I should just share it. I know nothing about music. Yeah, the interval is this a real relationship between two notes.

Right, yeah. Right. And um, and so they learn those two. Um, and you learn the scales and all that stuff, you learn it in a different way when you're young. But yeah, so if you but just out of context, they're doing a mapping to some category, whatever it might be. If it's you know, if you're Western music, then you're learning the the letters. Um, but then in another system you're learning it in some other different way, but you're mapping the the frequency to the category. So I'm I'm curious, so um what the relationship is between our representation of sound and the objective reality of vibrational frequencies. Because I know we were talking with Nick Graziano about the relationship between our

representation of color and the objective facts about uh color. And you know, we we're going into this this cool idea that like we we view white light as like a kind of purity or um absence of contamination, right? It's just like there's nothing there, it's pure and bright. But it's actually if you look into the physics of it, it's the opposite. White light is all the different wavelengths just sort of smooshed together. And it's weird that our representation of white doesn't quite fit the objective reality of it. There are plenty of other ways in which our representation of color doesn't quite fit the objective facts of color. Like, you know, if I see a red object in different lighting conditions, the frequencies of

light that are hitting my retina are going to be very different, but I'm still going to see it as the same color. This is color constancy. We see an object that looks the same, even crazy. That like the objective frequencies of light are totally different, and yet it seems exactly the same from our perspective because color is designed to identify and differentiate objects and not to necessarily accurately represent reality. So are there similar ways in which our representation of sound is different from the objective physics of sound, or is it more accurate than it is with color or or how do how do we think about this? That's a great question. And I don't think I have a great answer, other than I would suspect, I think it's more

accurate that those properties in the world are there to a more substantial degree. Whereas color is reflected off it. I mean, some would argue there is no color in the world in a sense, right? That we're it's like we're constructing it. Um and it does change in context considerably. I mean, you could there are contextual effects, I think, in in sound where um you know the same sound presented in two contexts would be perceived differently and then represented differently. Oh, interesting. So it's like sort of an analog to color constancy. I think there's some similarities there, though. I can't really come up with a really great um example exactly. But um in like auditory scene analysis, which is the study of how people perceive the

auditory environment, how you localize a sound, and how you decide that these frequencies could should belong in this or belong to this source, and these frequencies belong in this source, even though it's coming in as a wash of frequencies. We have this coherent separation of sounds that seems like that that sounds coming from there and that's coming from there, even though all these frequencies are all around you and you have to parse it. So, in that sense, you're constructing these representations of things that are probably um not completely accurate as a function of what they really are and what those things are emitting. Um, but I think it's more accurate than color. Color seems to me more constructed.

But that's I'm I'm not gonna bet much on that conjecture. But um I mean a fundamental frequency is a fundamental frequency, and I think we're detecting that in sources that have it um in a way that is pretty the the mapping is pretty isomorphic. Yeah. It I mean it seems like the the selection pressure for auditory scene analysis or knowing when certain sounds are coming from a particular source would be you know there'd be huge selection pressure on that. Like to know, you know, to differentiate the birds from the rustling in the leaves, you know, from the potential sound of a predator or someone else sneaking up on you, like being able to make those fine grained distinctions probably would have had huge fitness

implications. Yeah. So like how big is it? Yeah. How big is it? Yeah. Um is it approaching? Is it is it uh receding? You know, those are really important distinctions, you know, survival relevant distinctions. Uh yeah. Um But there are, I mean, that's you just brought up a good one, like John Newhoff stuff with auditory looming, right? We overestimate how quickly something will arrive and we don't have that same thing for a thing that's moving away from us. So there are gonna be various kinds of you know, air management issues and and uh distortions and yeah. Craig, I wanted to uh I wanted to ask um w either you can pick which one you want to do. One is I have this feeling that like vision science has its own conference.

Do do uh do acous does acoustics have its own science? And is it is large? Yeah. Like I feel like as an intro psych professor, I teach vision. I don't teach teach acoustics. I feel like acoustics gets the shaft a bit compared to like the other perceptions. Totally. The the main journal, the one of them, in my opinion, the best journal in the field for acoustics, Jazza, Journal of Acoustical Society of America, its impact factor is like 1.4. I mean, it's it's not um there's not a lot of work. I mean, there they there is a lot of different kinds of stuff, like underwater acoustics, and I mean, you know, it's a crazy field. And a lot of it is um not psychophysics, a lot of it's just pure, it's just you know,

engineering and yeah, it's other not psychology or even behavioral science at all. But um yeah, no, there is definitely an acoustics field. It's way smaller than vision. I mean, when you have like acoustics, acoustic perception, sound perception, that's definitely uh a lot, you know, there's a lot less work out there, a lot less people doing it. I I I realize this even because, you know, we've done work together. And even I did social categorization work where I started with visual cues like race or or team membership visually marked, but I wanted to get into accent. And then like starting to make the acoustic stimuli. And you know, I consulted with you about how to do it, but I realized like there is very

much a modality bias in the behavioral sciences, I feel like, at least from what I've seen. Um, and it sounds like that might be true. And is that because it's or why is that? Like I mean, it's a good question. Um what I do think is auditory perception and vision perception share this feature that they've made a lot of progress in understanding how the brain does it because of an inherent functionalist perspective from the beginning. Right. So people have been studying auditory perception since MLTs. And um, so I think we like vision perception, we have actually a better understanding relative to other areas of our psychology. We understand vision better because I think of the functionalist perspective and being able

to come up with theories that are testable about how, and then you can look at how it happens in the brain. Um, so there are auditory perception people out there. But um I think one reason, I mean you can say this for vision too, but I think what one reason is the technical, there's a technical constraint that you have to really get into the um the acoustic theory and you and you also have to um be able to learn how to do acoustic analysis, which until recently was actually rather hard. And this is a funny thing with Lita, one of her first papers, um she was doing analysis. And it's really I I love this paper, and it really was a huge, it had a huge influence on me. It's called Um Acoustic Invariances and the Expression of Emotion and Speech.

And she it was her honors thesis that she did in as an undergrad, posted JP, of course. Um, like all honors thesis is Um and I really love this paper. And then when I approached her early on and I was interested in working with them, and I she said that that gave her PTSD. I mean, it was so hard to do that analysis that she was like, I'm never doing acoustics again. She hated it because it was really difficult in those days. You didn't have software that did it. And so you had to actually fire up the oscilloscope. And I mean, it was kind of a nightmare. And so I think that probably had an impact on how people choosing that as an area of study because there was sort of a high learning curve, especially back in the day.

Now you have software packages that are relatively easy to use. If you know how to use R, you can figure out how to do a lot of these things. And Pratt is a standalone program that allows you to do acoustic analysis. And so more people are doing it, which has the downside of people doing it and they don't really know what they're doing. So, but more people are doing it because it is accessible. And so I I think that um it's probably going to get better, but for some reason a lot of people just are not drawn to doing that kind of work where you're doing psychophysics essentially. Yeah. That's what I like. Yeah. My I always talk about my favorite movie is Jurassic Park and watching I've watched it so

many times and like what I realized after watching it multiple times is the uh sound engineering is so important for highlighting and steel uh Spielberg does this with all of his movies is the sound tells you what to look at in the scene and you don't even realize it. But like, yeah, it's it's just such an interesting thing of like sound is so important. And but it f I it's just I I find it funny that it is so um there's so much instinct blindness generally, but then even like even among like behavioral scientists who take an evolutionary approach, there's like I feel like there's just not enough acoustic work, like it's like extra instinct blindness. Yeah, no, I agree. I mean, vision too, really, there's not that many people that are doing um vision

perception in the ebb psych. I mean, you have people in in doing cognitive psychology and psychophysics that do vision. Um, you know, like we had one guy in my department where I went to grad school, Bruce Bridgman, who was into evolutionary psychology too. But um, you know, they're almost nobody in EbSight does that, right? I mean, there was um Josh New Yeah did that kind of stuff and then he left academia. Russell Jackson sort of doing his Russell left academia too. Oh yeah, okay, yeah. And so and of two, if you go into vision, you're gonna leave. Yeah. Don't say that. Um yeah, so there's there's for some reason uh psychophysics is not really taking hold in evolutionary psychology, unfortunately.

I thought it would have been now, but yeah. Um, that that was, and I was gonna give you a choice, but that was the question. The other question, like, because this is a big hard question, and maybe we can just pause it. But my great mystery, and the thing I wanted to ask you more, is uh number one, what's up with music? And number two, I asked a bunch of people, like I told people you're coming on, and everyone wanted to know what your take on music was. And number two, what I find a mystery, and David has alluded to this, is number one, what's up with music? But number two, and equally, uh, why do why are emotions hooked up to these weird vibrations in the air, such that a vibration in the air

can make me feel a certain way and really feel that way in a way that so many other things cannot. Like that is weird. I would never have predicted that like from first principles, at least for me. Um, and it's in and it's just um inevit so obvious and it's such a weird thing, I I feel like. Yeah. So the you know, you're saying like vocal emotion communication or something like that. No, I mean like if I'm at a concert and there's a symphony in front of me, that symphony can connect to the colour. It's a powerful experience to hear this loud. Yeah, and it's just like that is such a while how how is that? Why why isn't evolving? Listen, all these different emotions based on the the type of you know the difference

between minor and major minor being more sad and gloomy like this is like it's so hooked up with the emotions like what what yeah yeah so well my take on it is that it's it's basically that vocal communication of emotion is underlying all of that and then cultural evolution has built I mean this is the simple answer we can get into it more detail but that cultural evolution has like built this whole um set of systems, technology and practices that have allowed us to make these huge sounds, like huge orchestras and giant sounds and movies and everything. But that the the underlying sensitivity to it is because we're sensitive to emotions and voices. And the reason that we are adapted to paying attention to emotion and voices because it's a

really good mode of communication at a distance in particular, right? You don't need to see my face. And so I can give you information at a distance and allow you to make judgments about whatever situation is going on based on my emotional signal. But I really think cultural evolution has then built on top of that this um super stimulus, right? So we have a sensitivity to the sound frequencies because we have to pay attention to other people communicating with us. And then it just has been elaborated. I mean, if you have a super stimulus, then you're gonna have a super response. I mean, that might not be the most satisfying answer, but I think that it's probably some version of that that we have the pre ad we have an adaptation for detecting emotions and

voices. Yeah, does that mean voices? This might be a dumb question, but like we also have uh words and linguistic labels for emotions. Like if I'm mad, I could say I'm pissed off. If I'm sad, I could say I'm sad. But if we just hear the words I'm pissed off or I'm sad, it doesn't have the same emotional effect than if I were to hear a symphony playing sad sounding music or like a punk rock band like playing angry sounding music with like a distorted guitar. Like there's something different about the sound than about the label, even though so like so so what's what's different there? Like what shouldn't the label be having the same effect if it has the same function to inform me about the emotion?

Right. I mean the label is conceptual, right? And so you're informing somebody of a concept that then they can figure out might have something to do with your internal feeling. But the sound is actually directly reflecting your feeling and it's inducing the listener. And so that's the ancestral um evolved capacity that's as old as mammals, where you by producing a fear scream, you induce fear in your audience, Right. Or even like a s a high pitched string that kind of sounds reminiscent of a s of a scream could have the same effect. Like the, you know, the the shrieking thing from Psycho that like the violin sounds a lot like a scream. Exactly. Yeah. Yeah. That's right. It's got high frequencies, they're dissonant.

Um, and so that dissonance is reflective of a highly aroused vocal communication system that's blowing it at blowing out the system a little bit, right? If I scream loud enough the amplitude is such that the waveforms can't resolve in my system. And so it's just like a speaker that can't handle the amplitude. And so you get this distortion that it that indicates you're overblowing the system. And that is going to be associated with high emotion. And then when you perceive that as an animal with um, you the ability to map that sound onto some sort of physiological state of the sender. And then that arouses you to actually have that state to some extent as well. So that's a very reductive stance to rock and roll and overdrive in rock and roll.

Yeah. So Paul, Paul and I have a paper on that exact topic that just came out recently. Awesome. cultural evolution of distortion. And yeah, it's I mean, maybe that's a sad for punk rock or whatever, but I mean that's so the so the hmm, interesting. So when we f hear a scream, we're responding not only to the pitch but also to the distortion. David, you're getting an exile. I think your mic is still on. Yeah. For some reason. Speaking of speaking of audio, yeah. We've never had audio issues before. Did it go away? Oh, I bring audio issues with me, man. Okay. That's weird. Anyway, um, so are we with audio issues? Yeah. So when we feel afraid at the sound of a scream, are w what is triggering it is

simultaneously the pitch and the distortion? Right. And which is a function of the loudness. Right. Um, but yeah, so there are not what we call nonlinearities. Um, this is kind of what in bioacoustics with the the category of different properties of sound that are have that uh association with harshness. So there are um subharmonics, there's chaos that's basically broadband kind of noise. That's the one that I think is most used in music. But then you also have um other kinds of um um sidebands and other little weird phenomena that are oftentimes just um bands of energy that are not in the harmonic series, and so they create they can create these sort of dissonant kind of sounds. Um but the the deterministic chaos is the one that I think is the closest

to distortion, which is just broadband noise. That's a great band name if nobody's done that. Broadband noise. No deterministic chaos. Deterministic chaos. So it's interesting. So in terms of you know the the evolution of signaling, what we're talking about is an indice where it's not necessarily a costly signal, It's just that there's something about intrinsic to the production of the signal that makes it a reliable cue of, say, physiological arousal, that just as a byproduct of the body amping itself up and pumping itself full of energy and tensing muscles and tensing vocal cords, it will, as a byproduct of that, uh raise the pitch and the distortion of what's coming out. Basically, Yeah. And I mean, I think these things um started as cues and then they get ritualized into

signals. And so then those nonlinearity, nonlinearity uh features, nonlinear features, um, would um be exaggerated, right? Essentially. Yeah, and so Greg, this byproduct idea or this elaboration, cultural evolution, uh, evolutionary byproduct idea, does it no? I I have two questions. One is is it is the idea that there are design features that it's really about con specific vocalization, or is it a broader thing where it could be other animals or or definitely could be other animals or even the acoustics of of non-living things? Or is it really seem like it's about um living vocalizations? Yeah, I mean I I think there probably are there's some general principles of the sound features of stuff in the world, you know, that you know if you hear a big sound like of

trees falling down, exactly that's scary and stop because it's derived from your perception of animal vocalizations. Right. So we get all kinds of kinds of auditory C analysis mechanisms that are um but the um but the emotionality but the emotionality of the claim is that it seems to have design features that are for the living world vocalizations. And and for the other animals as well as people, right? So if you interact with other animals, you want to know if you're gonna get bit. Yes. Order Or whatever. If other animals are screaming, that's important information for you as well. Yeah, seriously no, not my species. I don't care. I don't care. Yeah. I mean, um a big dog that is growling at me is going to scare me as much as almost any

person would. Yeah. Yeah. In the right context. Okay. Um though I might I I like dogs so much I might be like, oh come on, it's okay. You know but um so we definitely there there's uh actually an interesting uh paper um showing that people can detect arousal in vocalizations across the all animal kingdom. So even like insects make you know, and frogs and um birds and I mean all all kinds of animals have the same kinds of properties in their in their threat displays, which is th there's noise and it's loud, and people can arousal even in very distant animals. And so probably all animals have that basic ability. Is is interesting. So are is the thing that we're picking up on loudness and distortion that the louder and

more distorted it is, the more we infer physiological arousal? Yeah. I mean, to that's what we that's what has been shown now. I mean, I feel like there's another element that I've been struggling to measure, and other people uh nobody's really got a good handle on it, but it's vocal effort. And so you can kind of tell where in the range of effort are is a person at any given moment. You know, so if I'm really even if I'm in a distance and the sound is quiet, you can tell I'm screaming my brains out. Yeah. And it's not the absolute loudness that's giving you the information. And so there's something about telling where people are in their range. And I think it's true for pitch as well. So you can tell where people are landing in their their ordinary pitch range.

And we're usually more towards the low end, right? So I can go much more high than I can go down. Right. So I mean I could go down a little bit, but I mean um I can go I can get up there. And um so we can tell where people are are in their range. And so you know people like Dave Feimer and others have done research showing that when guys try to be lower pitched than they really are, that people can tell, even though they're not that much lower than their baseline. So if I'm just watching this all the time, it sounds like I'm trying to be low. And so I that w with vocal effort and also pitch effort or whatever you might call it, I think is an interesting thing that's really not been explored. And I think it's hugely important because how people manipulate that in a given context

could be important for, you know, figuring out what they're intending and Interesting. Can we um so it's it the I I really like the example of hearing a scream from far away that we still know it was a scream, even though it sounds quiet to the ear. It's sort of like a lot of things. Yeah, which is really interesting. I mean, it's sort of analogous to distance perception. So, like something that's far away, like a big bear that's far away, we can still tell it's big, it's a big bear, but but the the actual stimulus hitting our retina is quite small, which suggests that we have algorithms for telling us that um yeah, this may seem like it's small, but it's actually big and it's far away. Or s similarly, this might seem like it's a quiet sound, but it's actually a really loud

sound coming from far away. Like it seems like that would be pretty complicated. That's cool. Yeah, yeah. Like a train, you're like, oh, that sounds huge, but it's like not as loud as like the the baby that's a little bird talking or whatever, crying. Yeah, yeah. Yeah. I mean, with vision, you often have context that the sound doesn't provide. So if you see a bear, I mean, even if you don't know bears are big, you see a thing and you go, I can tell how far it is, I can see the trees, and that thing must be pretty big if I can see it from here. So you the context helps a lot. Whereas if you just saw a dot on a screen, a bear in a distance without any context, you wouldn't know. But if you heard a sound, no matter what, you'd be able to hear something without context.

Yeah. This is this is anecdotal. Um, but people talk about how cellos are very close to the uh frequencies of human voices, and that those are that is also very emotionally evocative. Number one, is that true? And number two, if so, is that evidence for that there is a privileging of like con specific uh acoustics in the emotional? I would argue almost all instruments are in the range of okay vocal production. But DiCello is probably um if you rank them, that would probably be up there pretty high. Okay. Um and so yeah, but most instruments are in are in the voice range. Okay. So if we if we were aliens, if there's aliens and they do music, it's probably gonna be their instruments are going to be in their con specific vocalization range.

Or that's not even sound. Sure. Non-sound music, yeah. That's interesting that there are a lot of logically possible instruments that we could have created, but but we didn't because they're not in the range. They don't emit sounds that are in the range of human vocal communication, so we don't find them interesting or engaging. Exactly. I mean we can have um instruments that play, you know, where the normal range is ten K or something, which is a super high pitch. We can hear it. I actually I might not be able to hear that anymore. But um, you know, normal people people under forty, whatever. Normal people under who are under forty. Yeah. Um there's a lot of people can hear ten K. And so you don't have an instrument that plays at ten K.

Yeah. Oh, that makes sense. That's that's super powerful. We want it, we want it in that sweet spot. And so what would be interesting would be just to see um, you know, show I mean all instruments have to play within this the scale too, the normal scale, which is A440 for Western music, meaning that the note of A is 440 hertz. So that's just right there in the voice range. But it'd be interesting to see the distributions of different instruments and then compare that to voices. And I betcha it would be the voice distribution would look like this, and all the other instruments would be all like this clustering around it. That's okay. Okay. So so fear is like you got the distortion, the vocal effort, and the high pitch.

It seems like anger would be similar components because when you're pissed off, you're also physiologically aroused and potentially ready to fight. But instead of a high pitch, it would be a low pitch because you want to convey formidability. Presumably, lower pitches uh convey larger size. And so anger would be something like distortion, vocal effort, and low pitch. Is that the idea there? Yeah. Yeah. Well, so loud and low actually correlates with physical strength. So if you can keep your voice loud and low at the same time, just loudness actually is the best predictor of physical strength. The louder you can produce a sound is actually correlated with your upper body strength. So how much can you bench press or how your hip strength or something like that?

Whereas pitch doesn't correlate with strength, which is an interesting thing that you would think is true, but it's not. Um David Putz and I differ on this a little bit. We debate about that because he's the only one that actually can show is ever shown that there's a relationship between pitch and strength. I've tried to do it a bunch, and I can't show that, and other people can't show it. So we debate that. He had, and now we have a paper actually together that I guess will come out someday that is a meta-analysis that is showing at least a small effect of pitch. I'm not really a big believer in the pitch strength connection. But could it be size? Could it be size rather than strength? Just like if you have bigger vocal cords, there's a bigger body, it's going to be more

resounding and lower pitch. And so it's, and you know, it's size isn't you know a kind of a cue of formidability, but it's not strength per se. Would you buy that? Um the problem is that vocal folds don't really scale with body size. Oh, interesting. Okay. Is it so you can have somebody who is a little person who has just the same size head and vocal folds as a person who's six feet tall. Oh, really? And so where is this? I have this idea like from Honey I Shrunk the Kids, when you shrink something, they go, Yeah, that that little tight. Yeah. Is that a myth? Like if you if you shrink something, it doesn't necessarily have to be a lot of if you shrink the kids with a magic machine, I think you might get a slightly different sound in

their voices. Yeah. Okay. But because everything is smaller, including the vocal folds. Okay, but the but the vocal folds don't necessarily scale with the rest of the body. Okay. They don't. And um actually the vocal folds are unconstrained by other um morphological features in the larynx. So you can get huge vocal folds that um are differentiated at at puberty from testosterone in in small people who are skinny, short, weak people can have like these ridiculous vocal folds potentially because of the actions of testosterone. Um so but testosterone doesn't really correlate with strength either. So higher testosterone doesn't mean you're stronger. Is it is it maybe picking up uh uh on just like adult maleness?

Yes. I think that's right. Okay. Yep. 'Cause that 'cause that would also be a cue of formidability potential. In the grand scheme of b the big picture of humans that yes. Yeah. Exactly. And so that's why you would see sex differences. Originally people showed that that low pitch was stronger, but then when you control for sex, that effect goes away. Um and so but the one the one thing I like about the I it occurred to me that you know what happens when people get stronger by training? What how does their voice change? And and it that that I think thought about that for a minute and I thought, okay, that's why a pitch is not a thing. When when you lift weights for a year and you get a lot stronger, your voice doesn't go

down, right? But you do get um better ability to push air with the muscles that control the airflow in your lungs. Those are stronger, and so you can push air out more forcefully, so then you could produce a louder vocalization. But then when you are produce a louder vocalization, it makes the voice pitch go up because that's one of the mechanisms of pitch change. There are two. One is um tightening the vocal core the vocal folds with these um muscles in the larynx. And the other one is just pushing air through the system harder. And then that makes the vocal folds vibrate faster. So when you go up in volume, you go up in pitch. And so it seems to be your ability to mediate that increase in pitch when you

increase the subglottal air pressure, it seems to be associated with actual strength. So keeping it loud and low at the same time. And then that relates to physical strength. Greg, what is format dispersion? You've told me for years, I still don't know what it is. And does that relate to physical size? And is that part of what we're talking about without using the technical language? Or is is format dispersion something different than size and strength and loudness? Um it it it's not I think there's a there's evidence that it's correlated with strength to the extent that body size is correlated with strength. Um so it's not giving you any other information. Formant dispersion essentially is the average distance between formants in the

signal. And the formant is a resonating frequency that is a function of the shape of the vocal tract. So you have the source, which is the air coming up from your lungs, it goes through your vocal folds, the vocal folds vibrate at a certain rate, and then that determines the source fundamental frequency. But then that sound goes through the vocal tract, through up your throat and out of your mouth, and there's these resonating um cavities in your mouth, in your nose, and in the back of your throat. And so those resonating chambers cause the signal to have certain frequencies be um amplified. I see. So those are the formants. And so the because it's just a physical um calculation of cow of seeing how

distant are those acoustically, and it's inversely related to the length of the tube. So formants that are closer together come from a longer tube. Okay. Yeah. And so just to analogize it in a guitar, like an acoustic guitar, you've got all the different uh frequencies or pitches being done by the strings, but then the body itself of the guitar is a resonating chamber. And that's going to in the and analogously, like basically our vocal cords are like the strings of a guitar and then our heads in a weird way are like a guitar body. Um I mean the guitar is a l is different enough where it's a little weird, but I think a better analogy is like a sax. Okay. Or an you know a wind instrument where this you actually have a source coming from the

mouth. I see, yeah. That's the thing you produce, and then it goes through the body of the instrument. Yeah, yeah. Cool. Yeah. Yeah. Cool. Yeah. So if you have like a bigger head, are you gonna make difference? Is it gonna that like a lower pitch sound? Like a more head, yeah. I don't know. Let's get some data. Get some calipers out. I mean that it I don't that's a that's I've never really thought about the big head issue, but yeah, probably that would have some consequences for sure. Um I mean a big head is gonna probably have a longer vocal track for one. Um but that's not quite what you're getting at. And uh um it's just like a more hollow head, like more space in there to resound, you know.

Yeah, the format dispersion intelligence hypothesis. Oh my god, it's yeah, a small brain, big skull. Um Yeah. Well, we're we're we're 25 episodes in or something like that. And now we're getting into bad episode. Okay. This is the line. All right, let's do it. Yeah, nice. Um, well, so you can see how format dispersion is related to body size, right? It gets it gives you a pretty much an index in the length of the vocal tract, which is correlated to body size. And this is true across mammals. Um, I mean it's not a huge effect, but it's much bigger effect than pitch for in terms of relating to strength and body size. Well body size even so low pitch isn't really related to body. So what what is it sound what is format dispersion sound like if not pitch?

Um so if if you heard the pitch of a sound, it would you know I mean I could if I was prepared I'd be like the timbre of the sound It's like the difference between baby cooing because we we did the Greg and I did the stimulant and I had the same question. And for me, at least, the intuition is you can imagine a baby like making a low pitch sound, but it kind of sounds like cooing, you know, like kind of like if you just imagine like a baby kind of making a noise vocalizing, but it's kind of a deep for a baby vocalizing, and then imagine like a whale producing, and you kind of get that. I don't even know how to articulate it verbally, but it at least it kind of captures like imagine what a baby sounds like and what a whale sounds like, but they're both making low

pitched noises. Yeah, though I mean, yeah, no, that's interesting. Uh is it like a kind of like um reverbiness? I think the the formant I mean, if you're asking what the formants are what they sound like relative to the source, think of just the source being something like I mean it's just a noise like that, maybe a little cleaner than that. It's it's formats being valves. So it's like AIO is I'm adjusting the the format. Um the I'm adjusting the formats because I'm adjusting the resonating chambers in my mouth by moving my tongue around and stuff like that. So the formats are like the vowel sounds that think about vowels changing across the different vowels. That's the action of formats shifting, especially the first Right.

And then the underlying pitch of the voice, which is just the source sound of, you know, think of it as it's not really any vowel. I mean, it's probably closest to ah, which is open, like uh the open. Right. So if I'm singing the same note and I go ah ooh e, like the the change in the vowel represents the ch the shift in the in the f format format. Right. Yep. Exactly. And so and then, you know, you could you probably inadvertently raise the pitch a little bit when you are like there's some sometimes you could there's a perceptual interaction, but I mean in theory these things are independent dimensions, the source and the filter. Um though E would sound higher pitched, maybe people might make that judgment.

Okay. Cool. All right. So we got we got fear, we got anger. What's going on with sad, lugubrious strings? Yeah. Or reflection. Or why does it make ref uh must reflect too? Because I think there's also like it's not just like seeing a snake, it also feels like it controls our thoughts to put it too s crudely. Um right? Like why do I feel reflective? Um that's interesting. Um, I mean, when you're sadness, you're trying to solicit um assistance at some level. If you take like the Ed Hagen-like approach to communicating sadness, which I like, um, there's something about you're expressing a a state that is not an immediate state about a moment where you need to act quick. It's more of a long it's a something about a long-term situation, and you're soliciting in

some way, or you need whatever you you um need at least um to check on who's your ally and and I mean there it depends on the context. But so I think that it I like the idea of it in invoking inflection or a reflection because you have to think about like what is happening, what is being communicated. It's not as simple as something like I'm going to attack you or I'm scared of a thing. It's it seems like it's about other more complex long-term phenomena. Yeah. And I don't want to be um like I we're we're all on this journey together. Like I don't want to do a gotcha thing here. Um and I'm not doing it in this spirit. But like one thing that I I I I'm puzzled by is why there's fluidity with first and third

person. Like, um, like why is it that if I hear sad music, I don't just react as if I'm hearing some something else that's sad. Why is it that it feels like it's in my head? You know, like I think that's the other part of it. Is like, why is it almost equally likely that it's almost as if this it's coming from me, which which feels right? Like, and I don't know if that's again or at the very least, like someone you care about. Like you could imagine like your enemy being sad and you not feeling sad, right? In fact, you might even feel happy because your enemy is sad, right? Yeah, but I'm like a whimpering animal. It's not like I'm like, oh, where's the whimpering animal? It's like who's sad around me?

It's like I hear sad music and all of a sudden I'm like starting to reflect on the things that either were sad for me or might be sad. Why is it in me? Yeah. I mean that that's a good question. I mean uh the first past answer is that it's it's also because of affect induction which is what I had mentioned before like the fear scream kind of makes scared, right? And because that causes an adaptive reaction. And so I think all of emotions are communicated, could have that kind of inducing effect, right? I mean, it's contagious. Um, and so sadness can be contagious, um, as can happiness. Laughter is very contagious, um, and um obviously fear and anger are contagious as well. And so I think what you're describing could be some kind of conceptualization uh or

conceptual um you know translation of this inducing sadness effect that would be my first past answer i have to think about that for a little bit though yeah i would sadness is an interesting yeah yeah i would i would also bet that sadness would be lower in vocal effort lower in distortion lower in volume definitely because in that case you're you what you're signaling is that you're not physiologically or that you're depleted down regulation in terms of Yeah, down regulation. You're you're defeated, you're tired, you're you're immobilized, you know, you're incapacitated, whatever. Like when you're in a sad state, your energy reserves are much lower, and and that is what is being signaled, presumably.

Like if you think if I think of like a lot of sad music, it's often very quiet. Uh uh Yeah. Yeah, exactly. And there's I mean, the the the melodic contours are very much like sad vocals, you know, sad speech. Um, and you were talking earlier about um, you know, w why certain um tonality or um how did you put it? I mean, there's tonality and scales and other kinds of musical features are associated with the emotions in the speech. So the when we're speaking in more sad tones relative to anger, for example, um, there are different kinds of frequencies that are highlighted that are associated with those kinds of melodies. And so like all these different kinds of musical properties are you can show have been

derived directly from the vocal expression of them. And so that Dan regulation, the dis descending contours and the melodies. And yeah, you don't have evidence of high arousal, so there's not distortion, you know. I mean a sad song with distortion ends up. I mean, I guess you could have sad punk rock or whatever, and it's that has distortion in it some level. Kind of sounds like laxymoron, yeah. Yeah. Like I can't I it's hard I'm having a hard time imagining like a sad electric guitar, you know? Or a a sad loud like distorted, yeah. Yeah. Then it's gonna sad. Yeah, there's it's definitely I mean you'd have to be pretty good to like get that across having th those kinds of characteristics. But it's also gonna be relative to other music that the person is producing, and then you

hear the relative emotion, even though out of context, maybe it wouldn't be taken that way, potentially. Yeah. There's there's another like really mysterious part of it where there's also like a sense of triumphant that you hear in music. Like when it shifts from minor to major, like it's like, ah, you've achieved something momentous. Like that is is really mysterious to me because that doesn't seem to relate to vocal effort or distortion or anything like that, which would be a valid cue of physiological arousal. That's something that's just purely in the tones and the change from uh you know minor to major. And that I have no idea what's going on. Do you have any idea what's going on there? I mean I I I think that um b positive negative um and minor major

have to do with positive and negative emotions in the voice again. And so when you're ex extremely happy, then you don't have those nonlinear features to the same extent than when you are, I mean, you do a little bit though. So people have done things like look at when people win in sports and other things. And they're definitely high arousal. So some of those nonlinear features are there just by by as a byproduct of the production. But you don't emphasize them in the same way as if you're growling at somebody or you are threatening them or whatever. So the triumphant positive notes are going to be cleaner, right? And then more negative songs or melodies are going to be more distorted and have different kinds of melodic

structure that's associated with that negative emotion. But I guess I would want to see the evidence for the triumphant thing. I I would assume it'd be a little more clean. You know, like horns, whatever, and um it's you know, like growling. Yeah. Is is there I mean, um, you know, if you there's certain traditions that are positive where it's a positive triumphant kind of thing and it's big sounds with like noisy features. So here's a here's a different, perhaps weirder question. If you rewound the tape of evolution um and you replayed it, could it be possible that um minor actually would connote happiness and major would connote sadness? Like, is this just an evolutionary accident? Is it arbitrary that these emotions are mapped to these melodies and sound structures?

Or is there something inherent to these sound structures that connects to a particular emotion? Right. I mean, that's a good question. And I think the evidence that I like, this is Dale Perves and Dan Bowling and others have done a lot of work looking at how musical features are related to vocal communication. And it's a very voice centric approach to music that I like. And their argument is that when you are producing emotions vocally like sadness or anger, that there um are the the relative frequencies end up mapping better to something like a dissonant musical key than when you have a positive uh vocal emotions, then those energy, those frequencies map better to um a major key. Um, so the idea there is that major and minor is universal to some extent.

And I think there's evidence that not everybody hears it that way. And there could be cultural evolution of musical traditions that make that small effect not so much an effect anymore. But my thinking of it is that it is derived from how these kinds of emotions manifest in the voice. And so there's really interesting work showing that if you normalize little tiny snippets of a voice, the acoustics, and then you convert the frequencies to just um uh octaves, So you have um ratios of frequencies that start at where the maximum amplitude is in the in the signal, which is used at pretty low frequency. And then instead of having the x-axis be frequency, you have it just be octaves. And then you take an octave slice.

Um, and if you look at that octave slice, the spectral structure, there are bumps that correspond really well to the chromatic scale. And so you can, you know, you octave is highlighted, the unison pitch is highlighted, and then a fifth is get there's a bump. And then all the little notes, there's a really cool figure in this one paper where they just show exactly how the little bumps in the spectral structure of a speech snippet is related to the chromatic scale and the Western musical scale. And then they can also do that same kind of thing for musical scales. So it's not just the intervals but the scales themselves actually there's there's certain scales um happen more often in cultural evolution than others, right?

They cluster, and the way they cluster is related to how the spectral features of speech map onto the chromatic scale. So to me, that's really that that we are really it's a cultural elaboration of this basic perceptual sensitivity to voices, and that we can cultural evolution can build so much richness and elaboration on just that basic um predisposition we have perceptually to that we like to listen to voices, or we have voice selective adaptations, right? I mean, that's that's super clear. Yeah, that's interesting. I mean especially the part where like sp speech corresponds more to it the chromatic scale than you know, say a major scale or a pentatonic scale or anything like that. Um like jazz to me comes to mind as like really making use of the chromatic

scale, making use of just like lots of tiny changes in notes and just ascending chromatically, you know, half step by half step. Um and to me, intuitively, jazz sounds more conversational. It sounds like the instruments are talking. It sounds like a person, just you know, like if you hear people jamming, it's just like the instruments are talking to each other, and it's just sounds like you don't know, more rich metaphor that jazz musicians like a lot. And they and I've I teach it that way in this one. I used to teach a class called group communication. I would draw explicit connections between conversational behavior and musical interaction. And yeah, they're you're taking turns and I mean there's all these elements they map really

well. Yeah. So um I think that we we're we're sensitive to voices and that that's the kinds of sounds we want to hear. We've we've culturally evolved instruments that are in the same range and that the way emotions are expressed are gonna if you would analyze it correctly you're gonna see map onto the way we express those things vocally. And so that's why we major minor consonants dissonance um descending versus ascending melodic contours, they just all seem to map. But then you have all these other features that cultural evolution uses to build musical traditions that then it's just it's crazy when you think about the music varia variability out there and that what basic adaptive problems and it that originally music solved is not

going to predict all the elaboration we see that culture has produced. And you just mentioned music being and solving an or was it a cultural adaptation? I mean, what is your take? So I mean there's one idea that you know cultural selection or biological selection uh made music an adaptation, you know, the big A, the, the A-word, the onerous concept. Um what is your take? So I mean there's one idea that you know music evolved for social bonding, for example. Um, I think what's your take on that? Um yeah. So there's there's a really good um BBS um thing that so um Max Krasnow and Sam and Ed Hagen and I um wrote a BBS Target article about this. And then it was, I think, the only time this has happened in BBS where we submitted two

target articles. So we did one and then another group of folks, um, Pat Savage and um Tecumseh Fitch and a bunch of folks um produced one that was about social bonding. Cause we did this conference in in Paris or outside of Paris many years ago where we were talking about the origins of music, and then two camps kind of happened us four, and then everybody else that likes social bonding. So we decided to do this BBS thing. They took both papers and then they solicited commentaries for both. And it's this huge, it's like a book. And um there we go after the social bonding idea. Um, and I don't want to pick on that here too much, but that the the idea is that um because they you can show effects of people playing music together, cooperate more and like

each other more, and there's all these sort of proximate effects, um, they argue that it's for that. And we make the case it's actually not well suited for that, particularly. Just because it has that effect doesn't mean that the adaptation is to cause social bonding. And we make the case rather that it's better to think of it as credible signaling. So when you have a practiced um effect of a coalition producing a coherent, obviously choreographed um show that it takes practice. It's an honest signal of time spent with one another. Um it gives an honest indicator of how well you coordinate your actions. And and so then you and the the idea is that that could have caused selection for the ability to entrain physically with another person, which is a

human specific um adaptation. No other, almost no other mammal can really do it well, um, where they can actually readily learn how to entrain to another person with their motor abilities. Um that's something that only people can do. And so if you're gonna look for a musical adaptation, I think you gotta look for why would people be coordinating their muscle movement like that. um in a super um fine-grained way. So that's the argument that Ed and I had developed a long time ago. It's my first paper ever published, arguing that it's you're giving an honest signal of coalition quality by coordinating your and music is a vehicle to do that. And then Sam and Max it's sort of developed this idea about how

infant caregiver communication caregivers signaling to infants that they um are actually honestly have their attention and that that promoted this uh motivation to produce melodies that that uh got the infant's attention and that it's hard to do that while doing other things. If you're singing to your kid you could be doing some other things but you definitely have you there you have they have your attention. And so it it that's an emotional communication mechanism that is sort of exploiting the predisposition for detecting emotions and voices, right? Some lullabies sound like friendly, affiliative kinds of vocalizations, but they're just um, you know, ritualized, highly ritualized. And so their argument was that that could be the origins of melody, is that the initial

singing between um kit for k caregivers singing to their offspring. So we just make the case that these are two examples of credible signaling that could form the basis for some adaptations that are actually for music. But then most other things that we incorporate into the music faculty, as they say, are byproducts of other things that we have. So that's my view view: that there are a couple adaptations plus cheesecake, right? And Pinker's idea of violatory cheesecake is sort of the hypothesis to beat, and that it's culturally cobbled together all these mechanisms that really have solved all these other problems. Um, and language is also possibly a lot like that. Like, what is what specific adaptation is there for language?

That's a big question. Uh, I mean, now it's getting reduced down to recursion, is the only thing. Um, even that's questionable. Um, language is a whole nother can't affect so I think there's a similar there's an analogous sort of argument argument there that you we're cobbling together all these abilities and culturally, but then there could be these core adaptive problems that that uh should be considered proper in the domain of music and not actual. And those sound like they're getting into uh time because you know, music is because the emotionality thing, there was no I mean, there was a little bit of a time commo component. But there is, of course, this whole thing of like rhythm or prosody.

Um, and just in in the, you know, somebody can't be a good musician if they don't have good rhythm or they don't have a good sense of timing, even if they're if they can if they're like, yeah, this pitch is gonna make you feel like this, if they can't do that over time, they're not gonna be a good musician. Um so, but but it sounds like dancing or like coordinating movement is an example. So is that correct that maybe these other uh proper domain-y things of coordination and possibly this byproduct of melody um is part of where timing comes in. Yeah, well, I mean the the timing is we humans are really even the people with the worst timing are um a pretty good relatively species, okay. Yeah, yeah.

Definitely. You cannot train a dog to play a drum, no matter how many treats. Believe me, I've tried cases. Yeah. Right. I mean, people have evidence for bonobos, um, which I mean, you don't see a bonobo in the wild doing anything remotely like that, but you can get them to kind of, you know, keep a beat along with the thing that they hear. That I don't think they've ever shown a bonobo being able to keep a beat without something to listen to. Um, there's evidence that sea lions can bob their head to a beat you know but it takes a lot of training and um and then birds can do it so there's the famous snowball the cockatoo who dances and cockatoos are well known to dance and so all these animals are

vocal sea lions are the exception which is an interesting one but um all these animals are vocal learners so um any animal that needs to pay attention to the periodic features of some other vocalizer, and then being able to make the same sound, and you have to learn how to do it. It's not something that's just genetically endowed. You actually have to experience the thing to produce it. Animals that do that can then keep a beat to some exogenous stimulus and then have the the the perception action coupling ability to then move their m muscles to the thing that they hear. But there's very few animals that actually have that ability. Sea lions are interesting because they are not vocal learners, but they are in their clad,

they're our vocal learners. So there's a latent ability in there that's not expressed in that species, but the the ability is clearly there. And then other related animals can do it, our vocal learners. So um I think the evidence is pretty good that vocal learning is important for entrainment. And so anybody, any human is at least is is kind of an expert in that sense, but then to be really good at rhythm is then you're tapping into like the best people. Right. Or maybe the emotional expression of like of like the timing of uh David, I know you're gonna say, is there any evidence of um emotion in music linkage? So like are really good musicians better at linking emotions and sound or emotions in general?

Yes. Yes. So trained musicians are better at identifying emotion categories in music and in voices. Not much, but there is an effect for sure. Cool. But then trained musicians are better than a lot of things. You know, it's like there's there's so many variables like when you're a trained musician, that's a pretty privileged situation. Sure. So you probably have a lot of advantages. Yeah. Um, and also um people you learn music, mu just learning music enhances other cognitive abilities. Um, it's sort of like exercises for the brain. And so um, if you're doing music, that's good for your brain and it activates all all areas of the brain, music triggers, unlike most other things. Interesting. Uh why do I remember so vividly and connect so deeply with the music I heard

during my teen years, maybe early twenties? Like I feel like everyone has that experience where they really connect with music at that age. Uh and like all their favorite stuff is comes from that era. Like, you know, my dad still listens to the the Beatles, like he's listened to that growing up growing up, and uh like all those old bands from the sixties. Um like what there's a strong age effect there. Huge. How do you have any sense of why that is? Yeah. I mean, I think this is it fits really well into the coalition signaling argument because think of music as cultural capital. You're learning the music of your culture. You have to learn the songs, you have to learn the scale, the musical system, right?

And you learn that like language. So as soon as you learn the musical system of your music, then you start being unable to make distinctions in other systems. And so you can't like Western music listeners can't hear that the sitar is out of tune, for example. Um there's kind of the famous story of Robbie Shankar tuning up his sitar for an audience and he finished tuning, but it clapped and then and George mortified and and uh and then he said something like Well if you like that I hope you really like the songs. So um we we are like language, we close ourselves off to other languages once we learn the distinctions that are important in our language. So think of that as like the musical capital that you've learned.

I like the capital idea. And so um during puberty, you're sort of there's I think like an imprinting process where the culture a lot of cultural phenomena, including t whatever it is happens to be in your culture. In our case, it's like TV shows and music and movies and um the th sayings and and accents or whatever. And clothes, yeah. Um y or memory systems are um there I think there's probably could be adaptations there that um are sort of imprinting those memories. So you remember the lyrics, you remember the songs in ways that you don't remember things later. And it's not just because you're getting old and you can't remember. It's there's something specific about that puberty old time. And so I think it's in an ancestral environment, that's just the way that you adopt the

culture that you're from and then you can honestly signal you're from it. Because if you come in as an outsider, as an adult, you won't have that effect. And so it would be easy to detect that you're an outsider. And similar to like um David Dave's work on accents, right? There's a certain thing about you learn accents, and it's hard to actually go into a group and pretend you're from there and have the accent. Like there's I don't think I could ever go to uh some village in England and pretend that I'm no matter how long I live there, they would always know I was not one of them. And so I think music's the same way. And that's that's the effect you're describing is basically that process of encoding the

musical culture that you grew up in. And so most people are like, music stopped being good after that, right? It's just like I predict like what when people think music started sucking is like when they were 30 or whatever. Yeah. Has there been work on them? Has there been work on exception? I'm always looking for new music, but the what? Has there been empirical work on that? very little actually there was a there was um um i i shouldn't say that there i was gonna talk about an ehb paper it didn't make it but um yeah not enough work on that i've always been fascinated with that idea and it's in some ways some aspects of that are quite tractable i mean you just ask people about what music they like yeah how old they are Showing showing the tendency would be easy.

If you if you didn't show it, you fucked up. I mean it's like Yeah. It's in the Simpsons. Uh so Homer Simpson, there's a classic quote from the 90s Simpsons that rock achieved perfection in 1974, right? Like when they're listening to music in the car. Yeah. So um, but then I think what is a more difficult thing is to try to measure um how that might impact other aspects of your judgment about other individuals and other social effects and I don't know. But yeah, uh that's a really interesting and super robust effect in my opinion. Yeah. Yeah, totally. I have a weird thing where I'm thinking I'm echoing again. Jeez. Um I have a weird thing where in addition to memor you know, remembering the songs of that

era very vividly, I have a really vivid memory of all the different film scores from that time in my life. If you just name one movie from like the late nineties, early two thousands, I'll be able to like tell you the hum the film score to it. Like even rent like speed, I remember the melody from speed, like from Keanu Reeves. Like I so it's a weird thing. I I don't know if that's a common thing, but like I have a really good memory for film scores, particularly from that time of my life, even if I saw the movie like maybe once or twice. Like Interesting. Yeah, I mean we and you you're obviously pretty into film, right? So then that's an attractor for you, right? Um, and then that example's interesting.

So I'm older than you, and so that is not a period that I know, right? I'm I wouldn't watching as many movies back then, and I certainly could not. I've seen speed maybe twice. And that's not true, but there's no way I couldn't even identify in a forced choice, probably. Yeah. Yeah. It's funny. Um, I I could talk about music the whole time, but uh, but I I know there's a lot of things that you've studied um in the acoustic modality that people are either sensitive to, um, that maybe may be surprising for people. Um are there are there ones that uh you think are cool or exciting? I mean they're all cool and exciting, but are there particular ones that either you've done in the past or that you're working on now?

You mean areas of research or topics? Yeah, yeah, yeah, yeah. I mean things you're doing or colleagues. But yeah, I mean I mean because I don't want to I don't want to have people just leave with the impression that you're doing just music. Um that's probably the the thing I've done the least empirical work. That's all I think. So I've done so yeah I do have some I have a couple papers on music perception stuff. Yeah and I think it's fascinating but I do want to like you know I I want to be able to talk a bit about what you've what else you've done empirically. Um so can you give us, I don't know what the best like, is there a story of like have you come around to like this this is the thing I'm focusing on?

Or is it just that there's like this you're a kid in a candy shop. There's so much to do. You have the lucky position of being an acoustic adaptationist and you're like, we're gonna do this and this and this and this. Yeah. Yeah. I mean, I guess I came into the whole thing interested in how people use their voice to convey emotions. And then the and and through music. So what what are the musical properties of speech is kind of a thing to think about. And so I got interested in prosody. That's sort of the interface between language and music. So prosody is this pitch and loudness and rhythm and some spectral features that are acting on top of utterances that give you information that's beyond what's in the language.

And um I think it's a super powerful mechanism. I mean, you can interpret a lot with from prosody without hearing any of the words. You can content mask speech and people are really good at identifying all sorts of rich dimensions about the speech signal just based on the melody. So I get that's what originally drove drew me into this whole area of research. And then Lita's paper um that I mentioned before was um you know focusing on that, looking at um how you know there's these certain invariances and acoustic structure across different emotions that are not about the language. And um in 1983, that was kind of a novel idea, kind of, and so um, yeah, so I got into that and then I started studying spontaneous speech.

And when I got my PhD in it's in cognitive psychology and psycholinguistics was the emphasis in the program. One of them, one of the big things. And so I started working with my advisor Jeannie Foxtree, who studies spontaneous speech, not from an evolutionary perspective. That was an issue, actually. But so we kind of settled on this topic of verbal irony and the idea of whether when people produce verbal irony spontaneously like sarcasm, are they doing some particular thing with their voice to express that indirect meaning? or is it an illusion, which she thought it might be an illusion because she studied what um syntactic disambiguation? So people think that when you have a syntactically ambiguous utterance, then um when you

say it one way versus another in context, people think they say it differently. But if you look acoustically, they don't. And so if I say a man eating fish, And people are like, and then you might think of a man eating a fish, or you might think of a shark, right? And people assume that you say it differently when it's one thing versus another. But if you look, they don't really. And so we kind of hear something that's not really there. So she thought this was true for sarcasm. And I didn't believe I thought sarcasm actually did have some special thing that was helping people understand that it was sarcasm. And it turned out we were kind of both right. There, it's less than you think. It's it's pretty ambiguous, but there are certain things that people do when they're

speaking ironically that are, I think, helping listeners understand it. So people slow down. For example, that's the one most robust effect is a speed change. And so when I was studying irony, and that was sort of the way I could get into experimentally looking at the effect of prosody on people's language processing. But then I noticed people were laughing a lot. And that was the signal. And so then that that got me going into like, well, where's laughter coming from? And then it there's there was uh some existing um literature on laughter as a play vocalization, which I was like, yes, that is it right there. And and that's now still I'm doing a lot of work like that, um, looking at laughter as a

play vocalization and non-human animals including. But um that's how I got into laughter is from this irony stuff. And then I realized laughter is this really understudied and super tractable vocalization that gives you a window into the evolution of vocal communication that's really nice because it's homologous across all mammals. But it's incorporated into our linguistic, you know, into speech. And then it also is a good example of a vocalization that is produced by the vocal motion system, which is a separate evolutionarily conserved system that is used to produce crying, laughs, pain shrieks, copulation calls. And then there's the speech system, which is a different control system for articulators in the larynx and the mouth for speech.

And it's a different system, and only one can actually control the vocal apparatus of the time. So that's why crying children and laughing people can't talk, right? Because that system is hijacking the vocal production mechanism. And so the speech system can't get in there. And that's why when you're talking and you're laughing while you're talking, then you're giving evidence that you're laughing in from the volitional system because it's actually happening with speech. Otherwise, if you're really laughing, you have to stop talking. So laughter is this really beautiful vocalization to study by looking at how these two systems interact. When we're unique in um all animals for having two vocal production systems like that, um,

this volitional system is super important for language and speech. And then turns out that I think one of the targets of selection for that volitional system is emulating the production of the vocal emotion system. So we do fake laughs, fake cries, fake orgasms, fake pain streaks, or whatever. And then that creates this whole extra level of dynamics if you're thinking about like game theoretically, and like how you're gonna understand the equilibria that emerge in communication systems. And when now we have this added level of volitional control that just makes it way more complicated. So you could potentially be faking almost anything. Interesting. So laughter is a totally cool vocalization to study for that reason.

And um now I'm studying, I've been getting more into bioacoustics. So um my grad student um is the director of a Gibbon Conservation Center in Santa Clarita, and so she's got 40 gibbons. And so I've been getting into gibbon and gibbons are interesting because they do a lot of dueting, so they do territorial um um displays, you know, mating pair duets, and they give information that this is our territory, and you can get inform you can glean like how long they've been together, and there's other aspects of their duetting that give you important information about the ecology. And they produce these other vocals, I mean the crazy vocalizations, these gibbons. And then I have a postdoc who is studying dog play vocalizations.

And this is more connected to laughter, where looking at dogs, and we just went and did some foxes last week. There's some Russian domesticated foxes down in San Diego. So I've been getting more into this non-human animal vocalizations and trying to connect those to things that we think might be true for human laughter and showing that, for example, domestication in play vocalizations and canids could be informative regarding the domestication of the play vocalizations in humans. And as a domesticated species, we've now um our a lot of our vocal behavior has changed, in part because we have this new speech system that allows us all this flexibility. So laughter is just just seems to always pop up and it's

it's fun too. Yeah. Um do you have any ideas about I mean I have ideas about why laughter is contagious and why hearing laughter makes you reciprocate it and why we you know you laugh and I laugh and you laugh and I laugh and we you know it's it it's this almost this kind of duet. Um I have ideas on that. I'm curious if you have any thoughts on that. Yeah. Well, I mean, I've heard, I mean, I I know your the theory, which I think is overlaps hugely with encryption. Yeah. And that's always been my approach is that laughter is um a signal of of decryption essentially. And then so you're giving covert um a covert signal of I have the information that you're referring to to explicitly state it. I know your thing is about mix-ups in particular, which we we could I think we've talked

about this a bit. We'll probably can talk about it more. I mean, you might say mix-ups are the higher the superordinate category, and I'd say encryption is. And so I mean we go back. But those are highly compatible ideas. Yeah. Um, so we're definitely on the same um wavelength on that one. But yeah, so laughter, I think, often functions as a way to signal to others that you have information without explicitly stating it. Um I also think that there's good evidence that laughter, co-laughter between multiple individuals can form a chorus signal that alert outsiders or give not alert necessarily, maybe sometimes, but more of like inform outsiders about the coalition strength of the people laughing.

Like you can detect how well for one, I have empirical evidence that cross-culturally you can detect how if people are friends or strangers in one second of co-laughter. Um, and it doesn't work like that with speech exactly. And so, but I think that um there could be some exaggerated features of laughter can be explained as being a signal for wide broadcast um and giving information about coalition strength that's beyond just friends or strangers, but you can actually get pretty rich information about the constitution of a group by just paying attention for a minute on who's laughing and and how loud. And so I think laughter is doing stuff that's outside of the immediate group that the laughter is occurring within.

Yeah, no, that's interesting. I mean, my my thinking on the topic is that um i if we mix up our meanings of a phrase, like for instance, you're confused about what whether hook up with means meet up with or have sex with, and you say you hooked up with my mother, right? Um if uh so that would be a pretty costly mix-up, you know, if you mix up those two meanings of of hookup with. Um and we uh we need some way of diffusing the costs of that mix-up so there's no grudge, it doesn't damage our relationship. And we not only need to diffuse those costs, we need to create common knowledge of the fact that those costs have been diffused. Like I need to know that you know, that I know, that there was a mix-up, and we're not

taking it seriously as actual communication, right? And I think that is is part of the function of laughter and why laughter is contagious. You want to reciprocate the laughter to to create common knowledge such that I send you the message and you send me a receipt of the message, and I send you a receipt of your receipt of the message, and so on. It's sort of like you know, Stephen Pinker talks about this in his new book, sort of like uh linking two electronic devices, or like you pairing two advice devices with the Bluetooth. Often they will send a message, and then the the the recipient system will send a receipt of the message, and then the other system will send a receipt of the of the receipt, and so

on, on and on until they establish a connection. And I think laughter is pretty similar and it's a way of creating uh common knowledge and sort of ascending the almost infinite recursion of n thoughts about thoughts about thoughts, right? Um so I think that's that's what's going on with with contagious uh laughter and why we we feel the need to reciprocate it. Um and uh yeah I'm curious number one whether cool um yeah I'll I should I just put out the preprint. Maybe I'll send it to you uh when when we're done. Um yeah but Yeah, you've been sitting on that for a while, huh? Yeah, I've been sitting on that for a while. Finally finished the damn preprint. Uh yeah. Uh I had to work through all the the math is was really a pain in the ass.

Uh um so that that took me a while to really finalize that. But um yeah, uh I'm curious number one if you you find that idea plausible and and number two, uh I I'm really curious about this uh distinction between fake and real laughter, and whether you think there's some kind of evolutionary arms race between fake laughters and fake laughter f detectors. Um if that's behind this and whether that applies to other kinds of vocal signals as well. Yeah, I think uh that it applies to all vocal signals in a sense that are um produced by both systems, right? Which is constrained by what the vocal emotion system produces, which is only nonverbal vocalizations. So yeah, I think it's the Athena activists and Naya have a paper that kind of started this

the spontaneous volitional laughter idea, and we talk about the arms race and that um clearly there is going to be selection to detect whether people are producing something volitionally that gives you information about what their potential intentions are. Now, how I think a lot of times volitional laughter is also just polite laughter that functions in a conversation and um is like a conversational marker. So it's not deceptive. It's not always going to be deceptive when I volitionally laugh. It's I can I can give like a little signal that I understand you, sort of like what the function would be in a for a real laugh, but I'm not emotionally triggered to do it. Instead, I just do it as a signal that is not honest in the same way, but I

mean then you could talk about the honesty there is that I think a complicated issue. But so it's not always a manipulative thing when we produce a volitional version of something that the vocal motion system does. Um I'm trying what was the first thing that you um whether you buy the idea that we're diffusing the costs of like uh uh either a miscommunication or or a faux pas or something like that and signaling that I like basically co-opting the play signal to to signal that you know we're not taking this seriously, just as the play signal often communicates, you know, this is not real aggression, I'm not actually chasing you or trying to hurt you. This is just pretend. I think that w uh evolution co-opted the play signal uh when we are mixed up with one

another or when we have a miscommunication to say to signal that we're not mad at each other, this isn't yes, uh we're not ta treating this as real communication, we're sort of treating it as a play uh interaction instead. Yeah, yeah. No, I think that's right. And so the mix-up thing I think is totally consistent with that. But I I also think there could be there are other reasons we laugh that have to do with social cohesion. So if you're with an old friend, you're not really signaling about mix-ups anymore, right? Um, if somebody I've known for 40 years, um, I think that even though it might be derived from that at some level, and you might be able to make an argument that it's sort of like

why do people laugh when they're by themselves? It's not obviously a different function, it's that there, it's as if there's another person there. So laughing with an old friend could be as if there's a mis a mix-up that we don't have. But I think it could also be that you are there, there's sort of endogenous reward when you're laughing together so there is a social bonding effect that can happen and so you might I I I think about like jokes between familiar people there the the mix-up angle I I'm gonna think of some good examples for you though and see how you answer them. I don't have them offhand but um I think there are examples of times where people are laughing a lot very motivated to laugh and there's not a mix up but um I have to think of

some good ones because I I know what you'll you'll be able to figure out the mix up if you dig deep enough. I which is a good thing about the theory. Yeah. Um, but I think there's other things about just mutually recognizing preferences, um, you know, or in some in some cases, like you might be critical of something that you both know. I know your view, and you know my view, and we each know that we know that. Um, and so there's no need to signal that exactly anymore. But there's still like has it that has a pleasurable um element to it that causes us to still engage in the signaling system. And so it could be that it came from a mix-up and now it's taken on this other kind of function, which also could be a motivating proximate mechanism for generating a signal that

other people can hear that gives information about our coalition status. So I guess that and that's consistent with your idea that it's not just about those people figuring out a mix-up, but and like I mentioned before, it's it could be about signaling something to other people outside of the group, which is why it's so loud. Right? Laughter is really ridiculously loud for what it should be doing. A better covert signal for the mix-up would be much quieter, like a play vocalization in most non-human animals. They're very quiet. They're not broadcasting that they're playing to everybody. They're only, and this is why they're hard to measure because you got to really get in there to record it. And it's hard to tell who produces it because they're barely, you know, and they're barely

moving your mouth. And so these are very dis they're um conspiratorial whispers, if you want to put it in the Krebs and Dawkins sort of language, um play vocalizations are. But but human laughter and some other species, only a few, are loud. So that suggests another function that's beyond the dyadic interaction. Yeah. So I would just say there's other reasons we laugh, but I I like the mix-up idea explains a lot, I think. Yeah, that makes sense. And yeah, uh if you come up with any stumpers, uh I'm I'm happy to hear them. Yeah, I'm gonna please please do. Science and action. Science and action. Yeah, no, my thinking with the the loudness is that um we coordinate and cooperate in much larger groups.

And if we're suffering a mix-up, uh the the people who are mixed up not only need to know it, but you know, all of their friends and associates and anyone who's nearby would benefit from knowing it as well because we coordinate as a group our our social conventions are community wide and not uh a function of you know two or three people. You know, we we share the same language as a community, and if there's a miscommunication, like we're all part playing that coordination game together of which sounds correspond to which things in the world. And insofar as there's a mix up between you know two people about which sounds correspond to which things, then the entire linguistic community has an interest in becoming aware of

that and avoiding that kind of miscommunication as well. So that would be my speculation for why um No, you should check out Tom Flampson has the empirical part of well, there's the first encryption paper, which was Tom and Clark did um that had some experiments about how much prior knowledge do you have and how that affects humor or whatever, um, supporting the encryption idea. But then he Tom has um other cross-cultural data from the people he was working with in Brazil, uh, who's the name of the group? I can't remember. And um, and he has these examples of in communities, large the the whole village is meeting and then people make these certain kinds of jokes that then cause people to laugh.

And he was analyzing like who was laughing at what and how that related to their social network. And um I don't know if you if you've seen that paper, but I think that would be useful for you to talk. I mean, I think your theory would fit well with that. Yeah, totally. I mean the other the other idea I had for why laughter varies in volume and why it might be louder in some contexts is if there's a larger cost to be diffused, you want to be much more certain that that cost has been diffused. And so you want to laugh louder and longer to really make sure that we both know that the other one knows that the other one knows that this that you actually didn't sleep with my mother, for example. You know, like the so the costlier the mix up is, the louder and longer we should laugh to

really make sure that those costs have been so hooking up with the guy's a taco bell is not as bad as hooking up with your mother. Yeah, but I think it's evolved from example that you like. Exactly. His workshopping the the his workshopping I've been developing my material yeah through traveling. I mean that's that seems like a pretty testable prediction right there. Yeah. Yeah absolutely that that would be a cool way to work out you know what you know, have a good convincing argument about what the costs are, which seems it seems like a hard problem. Uh yeah. And it seems like intuitive it fits my personal experience and and a lot of like anecdotes of like people when people really give a big belly laugh, it's usually at like kind of like

a like a dark joke or like a like a really like uh spicy, like costly mix up that that, you know, um we I it seems intuitively right to me. I don't know. Yeah. I mean, the the idea is similar to encryption in multiple ways, but one way is that people will have examples that at first pass seems to violate the thing, and then you can come up with actually that's encryption. And then you can show how it's encryption. It's not obvious immediately how it's encryption or how it's a mix-up. And so I think something to work out there is like what is the difference? Like are there encryptions that aren't mix-ups and are that but there's no mix-ups that aren't encryption. Um yeah. Uh yeah, I guess that's true.

Yeah. There there are no mix-ups that aren't encryption in some sense, and that you need to be uh privy to the coordination game being played in order to understand that there has been a mix up. Right? You need to speak that language, you need to be in that culture to know what was mixed up with what. And if you're not a member of that culture, you won't know. Um so yeah, I guess in that sense, all mix-ups are in encryption are encrypted uh, you know, among the people who are insiders to that culture. Yeah. Right. Would would would a would one let me just push on that though, and I'm the bystander here. Um, if somebody is like imagining like a new culture and they don't know, and the I'm just

imagining like this trope of like some westerner comes to like this very like belligerent culture where like they might kill the person and they're like the per the the westerner is sort of like says something which is inappropriate to the context, like oh nice weather we're having, a kind of laugh. You know, it's sort of a signal of like, I hope we're on the same page. Um, but they are laughing as sort of a gauge. Um, I mean, maybe that's a claim of like they're trying to probe for in um encryption, or that that's a affiliative, don't we have some common understanding? You know, um, some I don't know, maybe that's a a bad uh No, I mean I think that that fits within David's idea for sure. That you're you're you're trying to um exploit their their understanding of the signal,

even if the con they they we have mutual knowledge that the con we don't have the common ground to for the language to handle it, but then I'm signaling as if we do as a good thing. Like I'm trying now, it sounded like you're being insincere in your laugh. If you had a bad fake laugh, that might be costly, right? You're if you say something inappropriate and you're like or whatever, then you know that might be worse than not producing a laugh. So you better make it a good one. Yeah. Yeah. Uh yeah. The more I think about humor and laughter, the more I realize just like how unfathomably complicated it is. Like every joke is just like you could write a whole book dissecting why it's funny. And they do.

Yeah. And and just like the dove into the humor literature, I'm sure you have. Oh, I'm sure. Yeah. But even even beyond the funniness, there are like really complicated game theoretic constraints about like the incentives of different uh actors in the social network and whether they should laugh or whether they shouldn't or whether how loudly they should laugh or like what their interests are in in terms of whether they want those costs to be diffused or not, uh whether they should try to fake laughing if they don't get the joke, like really complicated considerations that I feel like with cost for whatever decision you make and then there um it it opens up a whole window of of costs and benefits that um hard

to go back on. Yeah. Yeah. I I think the um the volitional laughter adds so I mean volitional production of anything really adds so much complication there for sure. And there was something else I was gonna say about the laughter signaling, and then it I forgot, but I'll I'll give you a second because I just can't imagine I'm the humor literature I imagine has no jokes in it whatsoever. Like this I imagine like jokes are so bad. I I've generally yeah, I'm sure like I imagine like there's an entire book on humor, like the book, the blurbs in the back, like I didn't laugh once, right? Like something like that. Yeah, totally. Yeah, yeah. My my page, the preprint, uh has some genuinely funny funny jokes.

At least according to me, well, it has like, you know, all the movies that I grew up with, all the comedies, like, you know, Dumb and Dumber and stuff like that, uh, Seinfeld Seinfeld jokes. Um so I I like to think that the humor in there is is is funnier than the average. And then David, what you can do is you can be a testimonial, you can say this is scientifically funny. You could become that you're the you're the official if you don't recognize this, you are yeah, you know, technically have the bad sense of humor. Exactly. Yes, this is empirically funny. Yes, wonderful way to abuse my scientific credit credibility. Actually, that dad joke was funny. Yeah, you're you're actually mistaken. Well, and that's the thing about the both of these ideas.

Um, the the mix-up and the encryption is that it explains why jokes are not universally funny, right? I mean, it's all context dependent because it, you know, it depends what we're talking about and what the rules are. And um, and so yeah, no other theory of humor really has been able to point at that quite a bit. There are a lot of theories of humor out there that are approximate and capture some subgroup of jokes. And it's also the emphasis on jokes is is I think is big they've gone too far. The people that study humor um are thinking about the joke as sort of a proto humor. I that just that's not the way I mean, I think most people that study humor would realize it emerged first in conversational interactions that are context specific and that the joke

is a trope. Um but it seems like there's way more emphas like punchlines and all that kind of stuff. I mean yeah comic timing too is a super rich Yeah. Um that fascinating I'm I'm sure there's tons of like things you could do with that. I doubt you know people have done a fraction of of the experiments and and and studies that you could do studying comic timing. But like I mean my I I think it were oh let's go ahead. Yeah no most thing about it is it's just like micro mix ups. Like we have these conventions with like you know the timing of our speech, the speed, you know how much we pause, you know, vocal intonation. We just talked about, you know, how, you know, that your tone of voice uh communicates so

much. I mean you could have mix-ups there. Like you if I you know exaggerate um my my voice into kind of a s overly sing-songgy way, like that can be kind of funny. I'm like kind of mixed up about what the conventions are about how much I should change my tone of voice, you know, um, or if I you speak too loudly or too slowly, or if I pause in an awkward way. Like I think these these kinds of considerations factor into what we call comic timing, as it's layering in uh micro mix-ups about the uh the pacing and body language and intonation of the delivery of the joke uh on top of the content of the joke itself, which accentuates the the the comedy of it. And it's really uh the resolution of the timing is is incredible.

I mean, if you just wait an extra hundred milliseconds, it matters. And um so I've done some work looking at how um timing can affect pragmatic inferences in quick interactions of just answering questions. Um and you know, if you wait just a little extra in how you answer a question, it has all these implications for what kinds of implicatures you're communicating, um, what kinds of things the listener might draw from it. I use an example in my class of um if you say um just in a normal greeting, like, hey, how are you doing? And so if um like ask me how I'm doing. How are you doing? Good. Now ask again. How you doing? Good. And then ask again. How are you doing? Good. Right? So that seemed to be kind of a normal.

If you go too fast, it's there's all there's much different inferences you draw than and if I wait too long, then there's other complete. And the difference between those is like maybe was a 200 milliseconds, you know, a fifth of a second. Yeah. And so I think that basic principle of timing and pragmatics is then a particular feature in comic timing that's important. Totally. And if you're just a little bit off of what the the social convention is, it can be very funny. Like ask me how I'm doing. How you doing? See, that was funny. Like I didn't even wait for you to finish. So yeah. Yeah, there's so much there. Um I also have another pitch for you to work on differentiating um a hostile or e evil

laugh from a friendly or convivial laugh. I feel like that could be really interesting to look at. Um I mean my my my thinking about why laughter can sometimes be hostile or creepy is that uh mirth or amusement evolved to you know diffuse the cost of mix-ups. And in order to do that, it needs to deactivate uh regions of the brain that process costs. So deactivate negative emotions. So i uh the same thing goes with if you're playing. If you're having rough and tumble play, you want to deactivate your fears so you're not actually afraid for your life. You know, if you want to deactivate your anger so you're not like you know vengeful and retaliating against the person who's play fighting with you.

But in in the same way, if if we're trying to diffuse the costs of mix-ups, we want to deactivate those negative emotions, deactivate fear, anger, sadness, um, you know, uh w whatever. And uh the problem is though, uh, as soon as you have that machinery in place, um, that makes you very threatening to people who are not sharing your mirth. So if I'm laughing and mirthful, that means that my fear has been deactivated and uh and I could just attack you without fear of uh you know, retaliation. Um and my empathy might even be deactivated. If you're crying in pain or sad about something, like I'm not gonna feel empathy for you because I'm laughing. I'm mirthful. It's my those parts of my brain have been deactivated.

So for that reason, I think mirth can often signal that I have a lack of fear and that I have a lack of empathy for your suffering, and that makes me really dangerous. Um and so uh I I I would be I would be uh interested in in in maybe uh you know evil laughter having a different signature, or maybe it maybe it doesn't. I don't know. Maybe we just prefer evil laughter. Yeah, I think my most recent paper on laughter, it looks at that this issue, um, among other things, but looking at um whether people can distinguish between different laugh types that we've had people produce. So we create contexts where you know malicious laughter and um um co amusement and sarcastic and all these different things.

And it turns out that um it's really the dimensional view of emotion is the best way to to predict it. And in particular, valence. So it seems that LAF does work on the dimension of valence. So you can tell positive and negative, but we mix up positive categories at a high rate and we mix up negative categories at a high rate. And also with the machine learning algorithm, does the same kind of mix ups. And so we can see what the acoustic features are that are associated with these different laugh types, and then how those acoustic features predict it its valence almost completely, a little bit of arousal too. So the idea of a malicious laugh, like the whatever, is really a kind of a cultural invention that doesn't exist in ordinary discourse, usually.

But I think what you're saying is right in that a context where you're laughing and you know you know the other person's not laughing, and they know that you know they're not laughing, and then you might hike up a little more negative um sort of energy in there to make it sound a little darker because laughter could be very intimidating in certain contexts. Um it's not always positive, obviously. And so in fact, it could be linked to any emotion. But um, yeah, so I agree that that there could be situations like what you described where the laughter is really communicating something about your lack of empathy or your lack of concern for the other, and it's not about correcting a mistake. Um same way.

And but there's no categorical evil laugh. Um I think it's, I mean, other than in in movies that are you have to practice your evil cackles. Yeah. Nobody does that seriously, right? If you hear that, they're making they're doing the trope. Yeah. Interesting. But I'm sure it plays on, you know, like this, like I think it's what you're both saying, is like, you know, I mean, the tr a trope would be like you're a kid getting picked on, and and the kids who are picking on you are laughing, right? It's exactly what David's saying. I mean, that's the proper domain of this trope, right? Yeah. It's not that the that laughter is the cackle, but it feels like it. And then the trope, the the cackle sort of plays on that, yeah, elaborately.

Yeah. I mean, I wonder how universal it is. It probably would be recognized pretty widely. I mean, I imagine I always do the Schwarz test because I've been there and I can imagine how they'd react. And it's like, what would a Schwarr person, how would they react to like a prototypical malicious laugh like from the movies? And would they understand in a forced choice, is this happy or is this is this e bad well, it is happy in a way. That's part of the meaning that's part of the talking about they're happy that it's bad for you. Yeah. Like why why does everybody in your culture monologue when they're and tell the protagonists what they're about to do so that they can foil the phone. Yeah. Yeah, it might.

I mean you could ask, like, you know, what is the moral character of the person laughing? And like they might be able to say, like, that's that's a bad dude. He's gonna do some, he's he's gonna, you know, hurt some people. Yeah, he's happy doing bad. Although these days they might be like, Oh, isn't that the third uh Spider Man movie or something, right? Well, right, yeah, that those kinds of experiments are becoming harder and harder to do, yeah, to really get an isolated group. Yeah. Yeah. Even then, I mean, when I was down there 20 years ago, I mean, you know, I think somebody had a Madonna poster inside their hut. I mean, you know. Yeah. Subjectively. That's just the Chris von Rune thing where somebody who was like two days upriver and he

was like, Did you hear did you hear Michael Jackson just died? And Chris von Rune was like, What? And we actually checked because we had him on and I verified because he told me this when we were in grad school. It turns out he Michael Jackson had died and it just turned it just They knew before him. He they knew before him he had he actually left the um he had been on the boat and during that time Michael Jackson had died and it just transferred by word of mouth faster than Chris got there. Um so he got told some pop culture from oh two days upriver or something like that. That's the state of the world now. Yeah. And that was a while ago. Yeah. Yeah, yeah, totally. Uh Greg, we are getting toward the end.

We always have the question of should we have asked you anything? Uh I can't really think of anything offhand. It seems like you guys have covered it a lot. Um you know, I guess um you I guess you didn't really ask me about the non-human animal stuff. Um, but I mean I think there's an in uh sort of implied thing about the evolutionary history of these things is gonna um it's it's gonna be the case that a lot of the phenomena we see in human vocalizations are gonna be in non-human animal vocalizations. But yeah, is there something important or like that you think people it would be interesting to know about the non-human stuff? I mean, I guess uh when I think about it in terms of play vocalizations, I think the

interesting phenomena there is that the adaptive problem of signaling something about play is present, and then how it manifests itself in any given species is constrained by the communicative systems of that species. So play vocalizations have very different sounds across animals because they're incorporated into the vocal repertoire of those animals. And so the level of analysis there is more appropriate to think about the adaptive problem that's being solved. And I think that know, that's where the adaptationist program is key. And maybe a lot of people that study that stuff in non-human animals aren't always adaptationists. So you might miss um homologous features because you're not thinking about the adaptive

problem enough. Um I used to say laughter was just a homologous across apes, and that was sort of what people had suggested before I started thinking about this. The other people that had like Van Hoof and Provine and others, they would all really talk about um primates. And now I've become convinced. I have this recent paper I did with um anthropologist grad student Sasha Winkler looking at play vo like every single instance of play vocalizations noted in the literature that we could find, 65 species and all over the place, mammals mostly, but birds as well. And so the birds, I would say, are that's convergent evolution, but with all the mammals, I think those play vocalizations are homologous.

And I used to think that maybe like um play vocalization in rats saying rats laugh, which they do quite a bit. Um, I used to think that was an analogy that that was convergent evolution and it wasn't homologous, but now I've been convinced that it's homologous, but it's just different, so different, because rats are vocalizing in these high frequencies, and we people didn't even know they were doing it until they just by accident, like 25 years ago. Um, but the rat laugh is at 50 kilohertz, which is well beyond what we can hear. Um, and so but I think it's a homologous behavior, even though it's radically different in terms of the acoustic properties. So I guess laughter might be like a hundred million years old.

Exactly. Definitely. Now, whether we call it laughter or not, I mean, do we want to call what humans do something unique, which I think it is unique? Um, you know, some people say chimps laugh, and then that's fair because they're close. Um, but then do dogs laugh? And you know, I think you know, you get the risk of anthropomorphizing the behavior. Uh I prefer to certainly play vocalizations are you know probably a hundred billion years old at least. Yes. Yeah. Definitely. Yeah. Yeah. So that's a nice little behavior to study in humans when it's something that's that ancient, you know, and then it gets incorporated into even things like the conversational, like we're playing when in this in this conversation we're having right now, we're playing.

Right. There's all kinds of elements of play in there. And yep. And so it it's it's occurring at the highest level of communication, you know, it's in and getting incorporated into their repertoire. Yeah. Yeah. Uh do you you have music instruments behind you? Do you want to either plug any of your uh existing music or are you gonna after we start with it? So we mean plug it as in like promote it or plug it as in like plug. Well, actually, I meant they were both questions. I was gonna say promote, but then I there's a five year old. Yeah, exactly. It was a it was a mix up, Yeah. We will plug your work. Uh Greg has some cool music uh by the name of G. Bryant. Uh he's got an album called Soft Assembly of a Die Hard.

Um I was just checking it out before we start talking. It's good stuff. So and if you're listening, if you're listening, do check out the YouTube um uh for at least a moment to check out Greg's bass and banjo and um uh hollow body electric and there's a strat on the floor and or on the floor and then there's a a lap stop guitar right in the corner. Yeah. Yeah. Awesome. All kinds of goodies. It's uh I'm not too crazy with the guitars. I only have really one of everything that uh of its kind, mostly. Yeah. Um I have a couple basses, I guess. But yeah, I'm not like one of these people that has like a whole row of electric guitars that are all functionally the same. You know, it's just like this one's uh 1970.

Yeah, yeah. Yeah. But that's because you still play it, right? You you bought it and you play it. So you play them all, yes. Your parents were wrong. And I can I sell stuff too. I I unload equipment. Very good. Very good. Well, Greg, uh super cool. Um, really encourage everybody to check out uh Greg's work. Um, if especially if you're interested in anything acoustic modality, he is the that that that is his um he's the like the getaway driver of a heist movie. Greg is the um the audio modality um for for this neck of science. So uh it's super cool, Greg. I always love coming across your work and it's um yeah, it's I always like whenever I see your name on a paper, I'm always excited because I know I'm gonna learn something new and

crazy about nice compliment. Well, it's been fun. Thanks for inviting me. And um yeah, I'm enjoying um the other I've been watching some of these and um I'm enjoying them. They're good conversations. So keep it up. Awesome. Thanks. Thank you. David, it's funny to me that uh well, I guess if you listen to loud music, your your ears get tired, but just listening to something, you don't feel like your ears get tired. Yeah, if you're just listening to speech or to an interview, like city noise, like if you're overwhelmed, like you can have audio overstimulation if there's like too much music. That is true. You need a break, you need a bit of silence. Yeah, but it doesn't feel like it's in your ears.

No, yeah, I wonder it's kind of an interesting psychological question, actually. Like, w what is the function of sonic tiredness? Yeah, or perceived effort seems to be unique. There's certain aspects of perceived effort across different sensation or perception systems. I mean it might be it might be the opportunity cost thing. That like you know, you can only listen or focus on certain sounds to the exclusion of others. And if you're just like listening to this particular type of sound, you're eventually like the opportunity costs get pretty big if like you're not getting any more information from that sound stream. I don't know. Uh but so but it is the idea that like if you're just hearing one thing, Uh then

there's not competition for your attention, it's less fatiguing. Yeah. Maybe. I don't know. Maybe I'm just bullshitting. I don't know. Yeah. Well, a PSA is um if you have um after moving from Germany to the US, ever all this loud music and TVs in restaurants and third places. I hate loud restaurants, loud bars. Oh my god. There's a as David says, there's a loneliness epidemic. Please just turn it all off. Like let people just have conversations, please. Don't get me started. Ugh. And people have parties at these loud bars and you can't even hear anyone talking. Like what uh it drives me uh insane. Yeah. So just just turn everything off and let people interact. Yeah. Could not agree more. Yeah, great.

Um, I should end here, but but yeah, uh, please do Patreon. I mean that was very reductive, but yeah, we we have a Patreon account if you would like to um support the podcast. Um please visit that. What else can people do, David? Uh they can leave us a kind review. Uh they can say nice things about us on social media. They can send us an email if they have any ideas for topics or guests. That's pretty much it. Yeah that's great. And um yeah I just it was really nice to talk to Greg for two hours. I wish we could um Oh, I don't know, play out his his music, but you know what? I I I I don't know if you know this, David, but I've been playing the full um theme song at the end of the episodes because it's just so lovely.

Oh, thank you. That's nice. There's not enough Glockenspiel in life. I could not agree more. I'm a big fan of the Glockenspiel. Yeah, so sit back, relax, and enjoy the next 30 thirty some sorry, I cut you off about Glockenspiels. I don't want to cut it down. No, I was just gonna say it had a big moment in like the early two thousands, I feel like with the Harry Potter theme, you know. And then it just kinda disappeared. Like what the what's the deal? Bring it back. It's a beautiful instrument. So so that's our second rant here is uh turn everything off in these third places and bring back the Glockenspiel. Yep. Bring it back. Yeah. See you next week.