The sound of fear: Why so many animals scream

It's Halloween season — and what better way to celebrate October 13th than to explore the haunting sound of fear? That's exactly what we do in this episode, where hostRegina G. Barber https://www.npr.org/people/1082526815/regina-g-barber and NPR science correspondentNate Rott https://www.npr.org/people/348779465/nathan-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. Support public media with NPR+ and enjoy perks for over 25 podcasts like this one. This show’s perks include sponsor-free listening. Learn more at plus.npr.org http://plus.npr.org/. See pcm.adswizz.com https://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 https://www.npr.org/about-npr/179878450/privacy-policy

• 0:00Speaker 00

  This message comes from Planet Visionaries. Host Alex Honnold sits down this season with extraordinary doers creating real climate solutions. Listen or watch wherever you get your podcasts.

• 0:14Speaker 01

  You're listening to Short Wave.

• 0:19Speaker 01

  From NPR.

• 0:23Speaker 01

  Regina Barber here.

• 0:24Speaker 02

  With me, Nate Roth. Hello, Regina.

• 0:26Speaker 01

  Hey, Nate. I understand you're coming to us with some very Halloween-themed reporting today.

• 0:33Speaker 02

  That is right. Brace yourself, Gina.

• 0:35Speaker 01

  I'm bracing.

• 0:36Speaker 02

  Anyone listening, because today I want to talk to you about the sound of fear.

• 0:44Speaker 03

  Don't move.

• 0:45Speaker 01

  Oh, my gosh.

• 0:46Speaker 03

  Can't see us if we don't move.

• 0:48Speaker 01

  Is that Jurassic Park?

• 0:50Speaker 02

  You got it. It's not your typical Halloween movie, but I needed a good example of a scream. And I know that you, Regina, and all the Short Wavers out there just love dinosaurs, so I figured it would work.

• 1:01Speaker 01

  We do. We do. We love dino DNA as well.

• 1:03Speaker 02

  Yeah, point proven. There you go.

• 1:05Speaker 01

  OK, so this is a science podcast. What does the sound of fear, what does it have to do with science?

• 1:11Speaker 02

  OK, well, let me start by introducing you to the scientist who's studying it.

• 1:16Speaker 03

  I'm Dan Blumstein, a professor at UCLA. I'm a behavioral ecologist and conservation scientist.

• 1:21Speaker 02

  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.

• 1:27Speaker 01

  Cool.

• 1:30Speaker 03

  Have you ever been afraid of a sound? Has a sound ever scared you?

• 1:33Speaker 02

  But I first met Dan years ago for a completely different story.

• 1:38Speaker 01

  Was it like the smell of fear, like fear sweat?

• 1:42Speaker 02

  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.

• 2:06Speaker 01

  It sounds lovely.

• 2:07Speaker 02

  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 marmots.

• 2:17Speaker 01

  OK, I love the name. Let me look them up. Hold on. Yellow-bellied marmots. Oh, my gosh, they're so cute.

• 2:27Speaker 02

  Yeah, aren't they?

• 2:28Speaker 01

  They look like little beavers.

• 2:30Speaker 02

  Yeah, they're rodents, right? Like the size of a cat with shorter, stubbier legs.

• 2:35Speaker 01

  Yeah.

• 2:36Speaker 02

  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.

• 2:55Speaker 03

  Wait, is he calling?

• 2:56Speaker 01

  No, that one's calling.

• 3:00Speaker 01

  Oh, my god. Like, that little squeak, it scared me, actually, a little bit. And is it a trapped marmot?

• 3:06Speaker 02

  Yeah, so that's a pup. It's like the size of a gerbil or a hamster.

• 3:10Speaker 03

  You interview people, we interview marmots.

• 3:12Speaker 02

  So what is, why is it making that noise?

• 3:15Speaker 03

  This one's alarm calling. They can alarm call.

• 3:18Speaker 01

  Oh, my gosh.

• 3:18Speaker 03

  Pretty much from the first days they emerged from their burrow.

• 3:21Speaker 01

  It sounds like a smoke alarm.

• 3:22Speaker 02

  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-bellied marmots, that's just like, yo, hey, I'm letting you know something's going on.

• 3:33Speaker 01

  Somebody's trapping me.

• 3:34Speaker 02

  Yeah, in this case, somebody's trapping me. But it was a very different noise, a really startling one that really caused Dan to start investigating this bigger question about the sound of fear.

• 3:46Speaker 01

  OK, can we hear this different noise?

• 3:48Speaker 02

  Well, Regina, we got to give the people something to look forward to. So let's listen to it after the break.

• 3:54Speaker 01

  OK, all right. I guess I can wait 20 seconds. Today on the show, the science behind the sound of fear.

• 4:01Speaker 02

  And how universal those sounds are. You're listening to Short Wave, the science podcast from NPR.

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• 5:30Speaker 01

  OK, Nate, you've left us on this cliffhanger. What was the sound that caused Dan Blumstein to start studying fear?

• 5:37Speaker 02

  Yeah, so in the course of his marmot research, Dan has trapped lots of marmots, like thousands of them. And most of the time, they just make those little alarmed squeaks, the little fire alarm sounds we heard earlier.

• 5:50Speaker 01

  Right.

• 5:51Speaker 02

  But one time, he was holding this little baby marmot, and it let out something like this.

• 5:59Speaker 01

  Oh, my gosh.

• 6:02Speaker 01

  Oh, no.

• 6:03Speaker 03

  And I was sort of shocked by this scream and almost dropped this animal. I was holding it gently, and it screams. And I had this emotional response to the scream.

• 6:11Speaker 02

  So Dan says it's like the sound triggered something in him, like deep in his mammalian brain, which obviously made him curious.

• 6:20Speaker 03

  So I started reading and learning about screams. And it turns out that screams are very different than normal alarm calls.

• 6:26Speaker 01

  Yeah, like that normal call we heard earlier, that was just like a beep.

• 6:29Speaker 02

  Yeah, yeah, like the sounds you might hear from birds or squirrels when you're walking your dog, right? Like regular chirps.

• 6:36Speaker 03

  Screams are given when animals are under extreme duress.

• 6:39Speaker 01

  Oh, my gosh. Like me, when somebody jumps out from behind a desk or something?

• 6:45Speaker 02

  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 irregularities in the sound. He showed me spectrograms, like voice prints, where you can actually see this while the sound is playing.

• 7:06Speaker 01

  Yeah, I'm guessing nonlinear attributes are like sound that isn't smooth, like it's got some jagged parts.

• 7:13Speaker 02

  Yeah, it's like when you're looking at a sound file, right? And all of a sudden, you see this spike. So he explained it like you're listening to a podcast. Definitely not this podcast, because our producer Hannah would never let this fly.

• 7:24Speaker 01

  No.

• 7:25Speaker 02

  But a podcast where the microphones aren't adjusted correctly.

• 7:28Speaker 03

  And 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. You 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.

• 7:54Speaker 01

  OK, so what he's calling a scream is basically like your voice going above its normal operating threshold.

• 8:02Speaker 02

  Yes, exactly. Those nonlinear phenomena, those nonlinear attributes he's talked about, they show up across species. He's tested all sorts of species for this. It's true for marmots.

• 8:15Speaker 01

  Oh, my gosh.

• 8:16Speaker 02

  It's true for rabbits.

• 8:19Speaker 02

  And it's definitely true for humans.

• 8:21Speaker 03

  You hear that in Janet Leigh's screaming psycho. The shower scene was a real scream.

• 8:29Speaker 03

  You know, it's roadie.

• 8:34Speaker 03

  After that, it became, you know, good actor screams.

• 8:37Speaker 01

  Good actor screams. I like that. I wonder who like the best actor scream is like today?

• 8:44Speaker 02

  Uh, maybe like Florence Pugh in Midsommar. Have you seen Midsommar?

• 8:47Speaker 01

  No, I don't see like heady movies. I only see cartoons.

• 8:51Speaker 02

  Yeah, Midsommar is trippy. I would recommend it for anybody that hasn't seen it, but she's got a couple of really good ye screams in that movie. Uh, I think they should create a new Oscar category, you know, best scream.

• 9:02Speaker 01

  Yeah, next year, maybe.

• 9:03Speaker 02

  We'll table it, yeah.

• 9:04Speaker 01

  Yeah. But like, let's go back to these irregularities in like the sound waves. Like, you said that they show up across species, like all these mammals that you mentioned. Um, there's gotta be like a biological reason for this, right?

• 9:17Speaker 02

  Yeah. So Dan says it's because screams, this should be a surprise, are really evocative, right? They're hard to tune out.

• 9:24Speaker 03

  Baby cries, I mean, there's happy baby cries and there's really sad baby cries and upset baby cries. You know the difference. Um, you know the difference because you're attuning to those nonlinearities.

• 9:34Speaker 01

  Yeah. I mean, I, I definitely know the difference. Like when I'm sitting in a park or like at a restaurant, I, I hear a baby cry. You, you can tell if it's upset, right? Sad babies make me sad.

• 9:44Speaker 02

  Yeah, it makes everybody sad. It's triggering something in you. So it's a way for, you know, like 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.

• 10:05Speaker 03

  You can play back nonlinear sounds to even animals that don't vocalize, like skinks and lizards. And they respond differentially to the, to the noisy stuff, which is super interesting.

• 10:16Speaker 01

  Wow. So like even animals that like don't make these noises react to our like mammal screams.

• 10:22Speaker 02

  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-bellied marmot was making, 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-bellied marmots. And even that just added little like weirdness changed the behavior of the marmots and made them eat less. They foraged less.

• 10:53Speaker 01

  Wow. So like, it's not really the scream itself. It's like the weirdness of the sound that triggers the response?

• 11:00Speaker 02

  Totally. Yeah. So there have been like studies of meerkat 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-crowned sparrows, showing that they become way less relaxed when they hear these kinds of sounds.

• 11:17Speaker 01

  Fascinating.

• 11:18Speaker 03

  So we've done a number of experiments with people and perceptions of emotions, generated music, um, and film soundtracks that had, um, various types of nonlinearities. And the noise, rough noise, um, low fidelity noise is particularly evocative.

• 11:35Speaker 01

  This is like the, like, ch, ch, ch, ka, ka, ka.

• 11:38Speaker 02

  Yeah, yeah, exactly.

• 11:39Speaker 01

  Or, or like that eerie, like unnerving music that they play in those horror movies, like right before the bad guy jumps out.

• 11:44Speaker 02

  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 scream?

• 11:52Speaker 01

  Right. It's like eerie sounds, right?

• 11:54Speaker 02

  Yeah, that wee, wee, wee, wee.

• 11:58Speaker 01

  Oh, wow.

• 12:00Speaker 02

  Dan has worked with a film score composer at UCLA to test human responses to sound in like really benign videos.

• 12:06Speaker 03

  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, the noise starts at that five second mark, you think something bad is going to happen.

• 12:21Speaker 01

  Oh my gosh. This is like so wild, right? Because it seems like the horror movie industry like knows this already, right?

• 12:27Speaker 02

  Oh, 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 like nonlinear sounds show up disproportionately in horror movies.

• 12:43Speaker 01

  I mean, of course, now.

• 12:44Speaker 02

  Right, yeah.

• 12:45Speaker 03

  Again, I think I'm bringing the, a, 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, um, is useful.

• 13:02Speaker 02

  Yeah. I mean, Gene, it's, it's Halloween, right? So like tomorrow, people are gonna go around, they're gonna 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.

• 13:15Speaker 01

  I love them.

• 13:16Speaker 02

  I hate them. But, uh, I used to be a paper boy and it was Halloween was like the worst time of year for me because you'd like walk onto somebody's porch at four 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.

• 13:34Speaker 01

  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.

• 13:40Speaker 02

  Okay, yeah. So you are, you're a terrible person.

• 13:44Speaker 01

  Yep, yep, yep.

• 13:45Speaker 02

  But like, so I asked Dan, like, look, it's Halloween, right? So i- is it normal for any of us? Like, should we just embrace the fact that it's gonna scare us and know that that's, that's normal?

• 13:55Speaker 03

  And that's what makes us human. We are who we are because of who our 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. Um, so I think we should embrace our inner marmot and, uh, be happy that we're scared by those things.

• 14:17Speaker 01

  I am gonna fully embrace my inner marmot this Halloween and just like let myself be scared. Nate, thank you so much for bringing us this reporting.

• 14:26Speaker 02

  Yay, thank you.

• 14:29Speaker 01

  This episode was produced by Hannah Chen. It was edited by our showrunner Rebecca Ramirez and the facts were checked by Tyler Jones and Nate Rot. The audio engineer was Quacey 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 Short Wave from NPR.

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