Short Wave - The Sound Of Fear: Why Do Animals Scream?

Episode Date: October 30, 2024

NOTE: This episode contains multiple high-pitched noises (human and other animals) that some listeners might find startling or distressing.In this episode, host Regina G. Barber and NPR correspondent Nate Rott dive into the science behind the sound of fear. Along the way, they find out what marmot shrieks, baby cries and horror movie soundtracks have in common — and what all of this tells us about ourselves.If you like this episode, check out our episode on fear and horror movies.Curious about other science powering the human experience? Email us at [e-mail] and we might cover your topic on a future episode!See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

Hey, it's Regina Barber. Real quick before the show, which we should note has some scary sounds that some listeners may have an emotional reaction to. We'll explain later. I want to plug some other NPR content. It's been a wild election season. NPR has an around-the-clock election new survival kit for you from three podcasts. Starting with NPR's morning news podcast up first. It's recorded before dawn to capture the news overnight, and it's out by 7 a.m. Eastern. There's also the NPR Politics Podcast. with context and analysis on the big stories whenever they happen. So like, say you're confused about that breaking news alert. Look for the NPR Politics Podcast a few hours later. And finally, there's Consider This, the podcast where NPR covers one big story in depth every weekday evening. They'll be all over this election and its aftermath. So in the morning, up first.

Evening, consider this. And the NPR's Politics Podcast anytime big stuff happens. Okay. Thanks for listening. here's the show. You're listening to Shortwave, from NPR. Ooh.

Happy Halloween Eve, shortwavers, Regina Barber here. With me, Nate Rot. Hello, Regina. Hey, Nate. Nate's from the NPR Science Desk. I understand you're coming to us with some very, like,

Halloween-themed reporting today. That is right. Brace yourself, Gina. Embracing. Anyone listening, because today, I want to talk to you about the same thing.

Sound of Fear. Oh, my gosh. Can't see us if we don't move. Is that Jurassic Park? You got it. It's not your typical Halloween movie, but, you know, I needed a good example of a scream. And I know that you, Regina, and all the shortwavers out there just love dinosaurs, so I figured it would work. We do.

We do. We love Dino DNA as well. Yeah, point proven. There you go. Okay, so this is a science podcast. What does the sound of fear? What does it have to do with science? Okay, well, let me start by introducing you to the scientist who's studying it.

I'm Dan Blumstein and professor at UCLA. I'm a behavioral ecologist and conservation scientist. So Dan is all over the sound of fear. He wrote a book called The Nature of Fear. He's even given Ted talks about it. Cool. Have you ever been afraid of a sound? Does the sound ever scared you?

But I first met Dan years ago for a completely different story. Was it like the smell of fear, like fear sweat? I don't know what fear sweat is. I don't really know that I want to, but no, it was not about the smell of fear or fear sweat, I'm sorry to say. The story I initially met Dan on was a story about how climate change is messing up the seasons, how spring is springing sooner and the impacts that has on high alpine ecosystems, like the one I met him at in southern Colorado. It sounds lovely.

Yeah, it was awesome. So Dan has been leading one of the world's longest. running experiments on a wild species. And that wild species is yellow-bellied marmits. Okay, I love the name. Let me look them up. Hold on. Yellow-bellied marmits. Oh my gosh, they're so cute. Yeah, aren't they? They look like little beavers. Yeah, they're kind of, you know, they're rodents, right? Like the size of a cat with shorter, stubbier legs. Yeah. They're cuter than heck. And they usually live in these rock outcrops at high elevation. So he, like Dan, his predecessor, many graduate students, like Alyssa Morgan, who you're

going to hear in a second, they have been trapping yellow-bellied marmots at this site since 1962. Come on. Wait, is he calling or is this? No, no, that was fun. Oh, my God. Like, that little squeak, it scared me actually a little bit. And is it a trapped marmot? Yeah, so that's a pup. It's like the size of a gerbil or a hamster. You interview people? We interview marmots. So why is it making that noise? This one's alarm calling.

Make an alarm call. Oh my gosh. Pretty much from the first days they emerged from their burrow. It sounds like a smoke alarm. It does kind of sound like a smoke alarm, doesn't it? But as alarming as that sound might seem to you, Regina, to other yellow belly marmots, that's just like, yo, hey, I'm letting you know something's going on. Somebody's trapping me.

Yeah, in this case, somebody's trapping me. But it was a very different noise, a really startling one that really caught. as Dan to start investigating this bigger question about the sound of fear. Okay, can we hear this different noise? Well, Regina, we got to give the people something to look forward to. So let's listen to it after the break. Okay, all right. I guess I can wait 20 seconds.

Today on the show, the science behind the sound of fear. And how universal those sounds are. You're listening to Shortwave, The Science Podcast from NPR. Okay, Nate, you left us on this, like, cliffhanger. what was the sound that caused Dan Bloomstein to start like studying fear? Yeah, so in the course of his marmot research, Dan has trapped lots of marmits, like thousands of them. And most of the time they just make those little alarmed squeaks, the little like, you know, fire alarm sounds we heard earlier. Right.

But one time he was holding this little baby marmot and it let out something like this. Oh my gosh. Oh, no. And I was sort of shocked by this scream and almost. I was dropped this animal. I was holding it gently and it screams. And I had this emotional response to the scream. So Dan says it's like the sound triggered something in him,

like deep in his mammalian brain, which obviously made him curious. So I started reading and learning about screams. And it turns out that screams are very different than normal alarm calls. Yeah, like that normal call we heard earlier, that was just like a beep. Yeah, yeah. Like the sounds you might hear from birds or squirrels

when you're walking your dog, right? like regular chirps. Screams are given when animals are under extreme duress. Oh my gosh. Like me, when somebody like jumps out from behind like a desk or something? Yeah, exactly.

Like Dan says it can happen when any mammal, including you, overblows their vocal fold. So when they push air through their throat and out their mouth much faster than normal, it creates these like irregularities in the sound. He showed me spectrograms, like voice prints,

where you can actually see this. while the sound is playing. Yeah, I'm guessing non-linear attributes are like sound that isn't like smooth. Like it's got like some jagged parts. Yeah, it's like when you're looking at a sound file, right? And all of a sudden you see this spike. So like he explained it like you're listening to a podcast. Definitely not this podcast because our producer Hannah would never let this fly.

No. But a podcast where the microphones aren't adjusted correctly. It sounds noisy. It sounds rough. It sounds unpredictable. It's hard to discern. Those are attributes of nonlinear sounds. And you can think of a system like your car stereo,

it turn it up and it gets louder and it sounds great. And then you turn it up a little too much and it starts getting bad. That bad is predictably bad. And it involves a whole suite of acoustic things that occur when a system is sort of above its normal operating thresholds. Okay. So what he's calling a scream is basically like your voice going like above its normal like operating threshold. Yes, exactly. Those non-linear phenomena, those non-linear attributes he's talked about, they show up across species.

He's tested all sorts of species for this. It's true for marmots. Oh, my gosh. It's true for rabbits. And it's definitely true for humans. You hear that in Janet Lay's screaming, Psycho in the shower scene was a real scream. You know, it's, it's roadie. After that, it became, you know, good actor screams.

Good actor screams. I like that. I wonder who like the best actor scream is, like today. Maybe like Florence Pugh and Midsomar. Have you seen Midsomar? No. I don't see like heady movies. I only see cartoons. Yeah, Midsomar is tricky. I would recommend it for anybody that hasn't seen it, but she's got a couple of really good screams in that movie. I think they should create a new Oscar category, you know, best screen. Yeah, next year maybe. We'll table it, yeah. Yeah. But let's go back to these irregular.

in like the sound waves. Like you said that they show up across species, like all these mammals that you mentioned, there's got to be like a biological reason for this, right? Yeah. So Dan says it's because screams, this shouldn't be surprised, are really evocative, right? They're hard to tune out. Baby cries. I mean, there's happy baby cries and there's really sad baby cries and upset baby cries. You know the difference. You know the difference because you're attuning to those non-linearities. Yeah, I mean, I definitely know the difference. Like when I'm in a park or like at a restaurant, I hear a baby cry. You can tell if it's upset, right?

Sad babies make me sad. Yeah, it makes everybody sad. It's triggering something in you. So it's a way for, you know, a baby, a small animal, any animal, you know, to get the attention of the other members of its species or anyone else listening, right? Like, really get their attention. It isn't just an alarm call. It's saying that this is urgent.

And Dan says this works. And you can play back nonlinear sounds to even animals that don't vocalize like skinks and lizards. And they respond differentially to the noisy stuff, which is super interesting. Wow. So like even animals that like don't make these noises react to our like mammal screams. Yeah. The research suggests that a species will act differently because of the higher noisiness in a scream, right? The irregularities in the scream sound.

So like if you remember those alarm calls, a yellow belly marmot was made. the little like squeak, squeak. Dan has added like white noise to them, like irregularness, right, staticy noise, and he then played them back for yellow belly marmits. And even that just added little like weirdness, changed the behavior of the marmits and made them eat less. They foraged less. Wow. So like it's not really the scream itself. It's like the weirdness of the sound that triggers the response? Totally. Yeah. So there have been like studies of Mirkats showing that they are more likely to try to run away if they hear alarm calls that have added nonlinear phenomena, these nonlinear attributes.

Dan studied White Crown Sparrow showing that they become way less relaxed when they hear these kinds of sounds. Fascinating. So we've done a number of experiments with people and perceptions of emotions, generated music and film soundtracks that had various types of nonlinearities. And noise, rough, noise, low, Fidelity noise is particularly evocative. Is it like the like ch ch ch ch ch kaka? Yeah, yeah, exactly.

Or like that eerie, like unnerving music that they play in those horror movies, like right before the bad guy jumps out. Yeah, so like if you think about that shower scene in Psycho we heard earlier, right? Like what do you hear right before she gives that unnerving screen? Right, it's like eerie sounds, right? Yeah, that re, re, re, free, oh, wow. Dan has worked with a film score composer at UCLA to test human responses to

sound in like really benign videos. You know, a person walking and turning left and crossing the street, a person hearing a phone ringing and picking it up and saying hello and then five seconds before and five seconds after. And if the noise starts at that five second mark, you think something bad is going to happen. Oh my gosh. This is like so wild, right? Because it seems like the horror movie industry like knows this already.

Oh, yeah. Yeah. Yeah, Dan was like, listen, the horror movie business, like they know what they're doing. He's studied all sorts of different types of movies like action, horror, sad films. And he found that these nonlinear sounds show up disproportionately in horror movies. I mean, of course now. Right, yeah. Again, I think I'm bringing a deeper understanding of the biological basis, why we respond, how we respond,

which is in part based on an understanding of how these sounds are produced, and understanding that they're produced similarly under similar sorts of situations is useful. I mean, Jean, it's Halloween, right? So, like, tomorrow people are going to go around. They're going to be trick-or-treating. They might see one of those giant 12-foot jump at you sculptures, right, that now are sold at every store in the world. I love them.

I hate them. But I used to be a paper boy, and Halloween was, like, the worst time of year for me because you'd, like, walk onto somebody's porch at 4 in the morning, and you'd, like, step on the pressure pad that makes something, like the bat swirl around your head or something, and it would scare the living crickets out of me every single time. Me and my friend put spiders on top of these remote control cars and in the dark would have them attack people in her yard.

Okay, yeah. So you are a terrible person. Yep, yep, yep. But like, so I asked Dan, like, look, it's Halloween, right? So is it normal for any of us? Like, should we just embrace the fact that it's going to scare us and know that that's normal? And that's what makes us human. We are who we are because of who are.

ancestors were and not just our primate ancestors, but across the lineage of life. So everything jumps to those sorts of things, and there's a reason behind it. So I think we should embrace our inner marmot and be happy that we're scared by those things. I am going to fully embrace my inner marmot this Halloween and just like let myself be scared. Nate, thank you so much for bringing us this reporting. Yay, thank you. This episode was produced by Hanna Chin. It was edited by our showrunner Rebecca Ramirez and the facts were checked by Tyler Jones and Nate Rod.

The audio engineer was Quasi Lee. Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm Regina Barber. Thank you for listening to Shorewave from NPR.