THE HUMAN SCREAM

0:00This is an iHeart Podcast. Guaranteed Human.

0:31on the iHeartRadio app or wherever you get your podcasts. Welcome to Stuff You Should Know, a production of iHeartRadio.

0:45Hey, and welcome to the podcast. I'm Josh, and there's Chuck, and I'm not going to scream to start this off because I care about all of you listening. Yeah. That was a nice scream. Good for you. Yeah, we're talking about, Julia helped us out with this one, And I commissioned this one, and I don't remember what instigated it. It definitely wasn't from hearing somebody scream. I may have seen an article or something that piqued my interest, and I was like, wait a minute, what? Like, screaming is interesting, that people scream. And for all different kinds of reasons, people scream. And that's why I picked it.

1:26Here we are. Yeah, I was very surprised and impressed that it's one of those ones where you just think you know about it because you never really thought about it. And when you dive into it, there's a lot more to it than you ever realized. Although all of it makes sense anecdotally. You're like, oh yeah, oh yeah, I've done that. I've screamed like that. I've screamed and screamed and screamed again. Yeah, I like ones like this. I guess human nature explained. And there's a comma in there somewhere. Somewhere in there. Definitely not a colon. We should get some nuts and bolts out of the way as far as, like, everyone knows what a scream is.

2:03It's obviously a very loud, high-pitched, harsh thing on the ears. It's a sound that you make with, I was about to say with your mouth, but we'll get to the parts that make the scream. But nuts and bolts-wise, the scream is in about the 80 to 120 decibel range in volume. 60 decibels is normal speech, unless you're my wife. That's more like an A75, I would say. She and her friend, Stacy, are two of the loudest humans on Earth. And they admit that. They're not wallflowers. And they own it, and I respect it. Nice. They reach frequent, not Stacy and Emily, but humans, or I'm sorry, the human scream can reach a frequency in the range of 2 ,000 to 3 ,000 hertz, whereas a normal talker is about 80 to 300 hertz.

2:56Yeah, and for dum-dums with sound like me, the higher the hertz, the higher the pitch. So hertz is a measure of actual frequency. Pitch is basically a measure or a description of how we experience that frequency. That's right. And just to clear up something for what's coming later, a sound, a tone can have two different frequencies. I've got it. I have it now. Okay. That's it? No, I can't wait to explain it later because it's going to get flubbed all over the place. Well, it is. It isn't intuitive. Like you would think like a guitar string makes like, you know, one one frequency range. But it's just yeah, it's not true.

3:43It's one of those things. Yeah, it's just not true. We'll just leave it at that. But we're getting ahead of ourselves, Chuck. Yeah. Back to screaming, right? Yeah, because if you think about screaming, I always think of someone screaming usually in a horror movie or something like that. I haven't heard too many like real deal screams in real life, which is nice. But we're not the only animals that scream. There's plenty of other animals in the animal kingdom that scream that we know of. I'm quite sure there's plants that scream, too. We just can't hear them. Maybe. But birds scream, seals, marmots, mountain lions, and I didn't know giraffes scream.

4:23That's got to be off-putting. The funniest scream of all is a goat screaming. Yeah. If you have never witnessed a goat scream, go right now to YouTube and just look up goat screaming videos. And they don't all scream the same way, but every once in a while, one of them's going to come along and scream like a man. And it is like you will you can't not laugh out loud when you see it every time. I watched the same goat scream over and over again. And I laughed out loud every time I watched it. Yeah. And it's so non-goat sounding because it's not even like a loud bleat that you wonder, like, is somebody punking me?

5:03And that's just like, you know, that's James Caan from Misery that they're looping in there. Right. Does kind of sound like that. Another one to look up real quick are two lynx in Ontario screaming at each other. It's like right in their faces. Have you seen that one? I haven't seen that one. Oh, it's nuts. Animals, well, let's just talk about why anything screams. It's a very effective tool. It's obviously a great fear response because everyone's going to sit up and take notice because it's so harsh and loud. It's a very jarring thing. It can also distract predators. Obviously, screaming, if you're lost, you know, a scream can travel a great distance in the woods or anywhere.

5:46And you can, you know, alert somebody from a great distance. So it's a great communicative tool for humans and animals alike. Yeah. And that loudness, I saw the Guinness record for the loudest scream is 129 decibels, which is one decibel under a jet engine and almost 10 times louder than a police siren. I wonder who that was. I don't know, but man, I can't imagine that they did that too many times. Because as we'll see, screaming can really mess up your neck junk. Yeah, that's really gross. I'm getting older, so I'm getting more and more neck junk. I've got a lot of neck junk too. All right, so humans are born with this ability.

6:33We know how to scream right away because we come out of the womb screaming. In fact, that's a very comforting sound when a baby is born is that first scream. They're going to clear that phlegm in their airway so they can breathe. It lets everybody know, hey, I'm here. I'm ready for action. I'm feeling good despite the fact that I'm screaming. If a baby is born and there is no scream, that is a very scary, scary moment for parents and everybody in that room. Yeah, I can imagine. It's like the one time where not screaming means that there's an issue. Yeah, totally. And there's a lot of information in a baby's scream.

7:12It says, I'm in distress. I'm in pain. I could use a nosh. There's just a lot that makes a parent, because we're tuned to this kind of thing, especially if you're the parent of that baby. Studies show that you respond to your own baby's cries or screams a lot more easily or quickly than somebody who is not the parent of that baby. But you rush over there and you say, here's some food. Here's a little blanket. And way to go. You just got all the phlegm out of your throat. So now you can breathe normally. Yeah. I remember when you met Ruby as a baby and she was screaming and you're like, what the hell's wrong with this kid?

7:51Right. I just, you know, I tried to bounce her on my knee faster and it did the opposite of help. And I said, oh, Josh, I'm in tune already. Not in tune. Attuned already. I was also in tune. And I said, that just means she's hungry. So just raise your shirt. Yeah. Give her what she needs. That didn't work either. She got like hair in her mouth. Oh, my God. This got really disturbing very fast. Yeah. We got it out. What about that cat cry? So there is a syndrome that's colloquially called, I think, cri de chat, cry of the cat in French. And it has some similarities to Down syndrome. But one of the defining characteristics of crudus shot is a larynx malformation so that babies, when they cry, like the loud screaming cry, make a very specific cry that sounds very much like a cat crying.

8:47Yeah. Like you can find a couple of videos on YouTube of people with their baby with crudus shot crying. And it's really cute in a lot of ways. But also you're like, that sounds a lot like a cat. And it's so distinct that you can actually initially diagnose an infant with Crita-Shott syndrome because of their cry. It's that distinct. Yeah. So, I mean, that's a benefit that can save a lot of time and discomfort for this kid in diagnosing this kind of condition. Exactly. It's great. It also is a sign, obviously, when a kid is screaming, saying, hey, parent, go into fight or flight mode because I need something.

9:29and, you know, if it's one of distress, even more so, obviously, and not just like I'm hungry, like severe distress. I don't know that we need to discuss fight or flight in detail because we did it 364 times over the first, like, five years of the show. Right. Everyone knows what that is, right? Yeah, I would think so. I don't think we really need to describe fight or flight. You're like, but it's the amygdala. I didn't. I stopped myself. I exercise great restraint. Nice work. Okay. Well, anyway, I'll take it from here, Chuck. Yeah. Because the reason you brought that up is screams activate fight or flight mode in some really, like, basic ways, as we'll see.

10:10And so a scream actually activates in you a human who hears a scream that readiness to, like, either spring into action or run like hell or freeze or fawn is the other one now because the fight or flight syndrome has really come a long way since we last talked about it. And fawn is the response that you want when a baby's crying. You want to go over and be like, oh, it's okay. Yeah, that's right. Here, never mind. I'm going to abandon that line of thought. I think you should. So let's talk about sound for a minute because all sound comes from and is perceived by us through a series of processes in the brain.

10:51And most of these are in the higher brain region, but screams are different. They happen in the lower brain region. And it's a very interesting thing. It kind of lives in its own, as far as like humans making sound, lives in its own area. It's very distinct from all the other sounds we make. Yeah, and it's a lot faster to basically activate us than the normal speech that we hear, right? So when you talk, when you're making just talk, like I am right now, say. This is a good example. I'm using this description as an example in real time, okay? That's right. So I'm using my laryngeal motor cortex.

11:30That's basically running the show right now, and that is a higher brain process, right? So I'm using cognition. I'm figuring out how my mouth should move, which also requires fine motor coordination. I'm processing sound. I think from our internal dialogue episode, I'm doing a quick quality check right before I actually say the words. Yeah, sound like Josh. Exactly. And do I sound like a Muppety tenor? I do. Let's go. And then this stuff is sent to the brainstem, which basically says, OK, larynx and vocal cords and lungs and abdominal muscles, let's talk. That's normal speech. And again, it requires a lot of higher brain processing.

12:10Screaming uses a different set of equipment to make itself happen. It's nuts because you think screaming is a form of speech. It's actually not, even though we use a lot of the same stuff, a lot of the same bait and tackle, say. Like it's its own thing, which is I just find this is where I'm like, OK, this is super fascinating now. Yeah, that's right. So for screams and some involuntary vocalizations, but really screams, the sound production takes a different and like you said, a much faster path. The signal starts in the limbic system and it skips that higher brain processing. It happens in the amygdala, basically.

12:53The emotional stimulus that the amygdala is all about just sends a scream signal. It's sort of like a direct path, like a express train through that brainstem to all the anatomy that you were talking about and your in your, you know, the neck junk. And that scream just comes out immediately. And the craziest part is our body actually picks up on this before our ears and brain can even process what we've just heard. Yeah, once the scream comes out of someone else, when we hear that scream, it puts us in fight or flight mode before we're even consciously aware that we have heard a scream. That's how finely tuned we are to responding to screams, which again, this is something you just think exists out there.

13:40And then when you dig in, you're like, my God. So there's like a whole set of processes that take place that, again, are different than how we would respond if we hear regular speech, right? So it follows some of the same processes. It hits the outer ear, goes through the ear canal. The eardrum goes boom, boom, boom. That is amplified in the middle ear. And that goes on to the cochlea, which triggers a wave along the basilar membrane, which says, I'm going to turn this into an electrical signal, sends it to the auditory nerve. which sends it to the brainstem and then to the thalamus. And the thalamus is the sensory clearinghouse.

14:18It sends this to that and that to that. All of your sensory information goes to the thalamus. And here is where it diverges from normal speech. Yeah. And I mean, that's why when somebody screams like a blood-curdling scream out in public, you're instantly reacting. You don't hear that and then decide like, well, maybe I should go see what's going on over there. like your body's instantly reacting because it is unconsciously picked up on that scream before it's even registered in your brain. So it's it's really a pretty remarkable sort of evolutionary trait, I think, like to to to help rescue, you know, probably back in Tuk Tuk's days, the wife or baby that the the husband who's out hunting and gathering has to protect from whatever dangers are around the fire.

15:05Yeah. And the reason why that happens is because when it hits that thalamus, it gets sent two different ways. Like it gets sent the normal way to that higher brain processing. And when it goes through that higher brain processing, that's when you become conscious of hearing that scream. But what's happened even faster is it got sent to that amygdala and that sent in the fight or flight response. And that happened before your higher brain finished processing, which is just it's so there's this own pathway for just screams that the human brain has evolved to basically make you able to respond to a scream faster.

15:46It has its own expressway. Screams only, essentially, is what it says. And if your regular speech, you try to use that same expressway, it's got those tire bursting spikes that will just stop you cold right there. And they'll send you back along the way you're supposed to go to the higher brain. You go back to talk town, buddy. Exactly. And it's going to take you a while to get there because you don't have tires. You're driving on just rims now because you were dumb and you made a poor decision. Yeah, and you shouldn't do that because you're going to damage those rims. You need to pull over immediately.

16:18Yeah, it's bad. Should we take a break? Yeah, I think so. All right, we're going to take a break and come back, and Josh is going to explain something called the roughness domain right after this. Learning things with Chuck and Chuck. Shining all the things. Stuff you should know.

16:42Hi, Kyle. could you draw up a quick document with the basic business plan? Just one page as a Google Doc and send me the link. Thanks. Hey, just finished drawing up that quick one page business plan for you. Here's the link. But there was no link. There was no business plan. It's not his fault. I hadn't programmed Kyle to be able to do that yet. My name is Evan Ratliff. I decided to create Kyle, my AI co-founder, after hearing a lot of stuff like this from OpenAI CEO, Sam Altman. There's this betting pool for the first year that there's a one-person billion-dollar company, which would have been unimaginable without AI, and now will happen.

17:17I got to thinking, could I be that one person? I'd made AI agents before for my award-winning podcast, Shell Game. This season on Shell Game, I'm trying to build a real company with a real product run by fake people. Oh, hey, Evan. Good to have you join us. I found some really interesting data on adoption rates for AI agents in small to medium businesses. Listen to Shell Game on the iHeartRadio app or wherever you get your podcasts.

18:03All right, Chuck, here we go. Here's the flubbing. Okay. Well, we'll see. It's a little brain breaking, but we'll get it. I think it's one of those things where if I just thought too hard about it and I've made it brain breaking. But so so screams have something in common, and that is that they exist in a region of human perception that's called the roughness domain. OK. And if you take someone's voice. Right. It has a certain frequency. my voice has a certain frequency, you can recognize it as mine, but you can take my voice and make it modulate, right? So like the British police car that goes, that's modulating, right?

18:51So it has its own frequency, right? But you're making it change pitch. So that's a second frequency that it has. And if that frequency is between 30 hertz and 150 hertz, that modulation between up and down, or left and right, however you want to look at it, that is that roughness area. And it also seems to be reserved, as far as human sounds go, just for screams. Yeah. There was a study. They learned this because of a study. Whoa, whoa, whoa. How did I do? Oh, you did great. Okay, good. I'm sorry. I didn't, the customary. Thank you. We usually edit the claps out. I think we should leave that one in.

19:34Yeah, yeah, let's leave that one in. They know this because in 2015, NYU, the neuroscientist there, published a study supporting this role of amplitude modulation. And the crazy part is that the only other sound in that roughness domain, like that's the only sound a human can make that's like that. The only other sounds are all artificial alarms. So the human screen lives in the roughness domain alongside sirens and car alarms and, you know, just other, like a klaxon maybe. What is that? Is that the bad guys in Doctor Who? I think a klaxon is the... Oh, those are terrible. Like pull your credit card out of the card terminal?

20:20Does it actually do that? Yes. They did originally. I think they kind of stopped, but it used to be really jarring. Yeah, I mean, because that's the sound that happens when a nuclear facility is melting down. Right. Forget your credit card, melt down a nuclear facility. Basically the same thing. Yeah, so thanks NYU for that, right? Well, okay, that was just part one of this study. This is a really robust study. So they analyzed recorded sounds, and they found that screams were all in roughness, and the only other sounds that were in there were alarms, right? Then they got a bunch of volunteers, almost guaranteed NYU undergrads looking for extra credit.

21:00And they said, we want you to make a bunch of sounds. We want you to scream. We want you to speak normally. We want you to scream, speak. Yeah. And make a bunch of meaningless vocalizations like yips, yammers, yelps, that whole thing, right? Sure. And then they analyzed those just like they analyzed the recorded sounds. And they found that all of the scream sounds were in the roughness domain. And all of the non-scream sounds, including yips and yammers, were not in the roughness domain whatsoever. So they're really zeroing in. And yet there's more to this study. This is how robust it was. Yeah.

21:36So then they said, all right, we got out this collection of sounds. Neutral sounds is what we'll call the ones that aren't screams. And then the screamy things. and they brought in some other volunteers, other NYU students, for sure, and said, all right, we want you to rate the scariness, like maybe on a 1 to 10, 1 to 5, who knows what they used. Maybe a Yelp star system. Okay. And they said, rate the scariness of the sounds. All the sounds in the roughness domain, this is pretty obvious, were rated as scarier than the neutral sounds. And the sounds that were rated the scariest were the ones that were highest on the roughness scale.

22:11All make sense. Right. So they're really drilling down here. It keeps going, everybody. They actually took volunteers, probably the same ones who rated the scariness of the sounds, and they scanned them while they were listening to scary sounds. And not just screams, but also artificial alarms, too, and probably some of the nonsense sounds and musical sounds. And as they were listening, the screams and the alarms were the only ones that caused spikes in the amygdala. Remember, the amygdala is where that set-aside pathway for screams is. And that the higher on the roughness scale, if you can call it that, that the screams or alarms were, the greater the amygdala activity.

22:53And then the greater the amygdala activity that was shown in the scans, the higher those sounds had been rated for scariness by the volunteers previously. And when they wrapped it up and put all this together, they were like, I forgot what we were studying in the first place. so the upshot to to borrow a term from josh is that it seems like humans are uh specifically attuned um and our amygdala is specifically activated by the sound of a scream uh to say like hey it's time to panic or it's time to to kick into high gear they found that this works if you're awake or asleep, the rough vocalizations and that rough domain that we were talking about penetrate human sleep cycles more than neutral vocalizations.

23:48And that's not to say that, like, yeah, of course, it's louder, dummy. We're not talking about decibels here. We're talking about a frequency range. Like, I think of what they're saying, and correct me if I'm wrong, is that a scream that might be the same decibel level as, like, a really loud talk will penetrate that sleep cycle unlike that really loud talk. Yes, and they think it's because the amygdala is tuned to that 30 to 150 hertz roughness band. So the amygdala has its own route for getting you aroused, and not necessarily in the best way, when you hear a scream. And it's also listening out to a specific band of modulation to that scream's existence.

24:30So clearly, thanks to our NYU researchers back in 2015, screams are a really important and kind of overlooked part of human speech right and yeah for sure and they think also chuck that not only has um like have we evolved to develop this alarm system which clearly is what it is because not only are you saying help you're also depending on how nice or altruistic the people listening are um you're also saying look out there's danger and They may run away if they flee, or they might run to you to help you if they're ready to fight. But they also have shown that screams have evolved in other ways, too.

25:12Like, we don't scream just out of an alarm system anymore. There's actually at least six other screams that they discovered that correlate or correspond to six other separate emotions. Yeah. Anger, of course, is going to be one. You can scream at somebody in traffic. There's a Europe song called Scream of Anger. Really? And Europe, of course, is known for a different song. Yeah, but you know what? I heard, oh, what was it? That other Europe song I forgot about the other day on Hair Nation, on Sirius XM. Okay. Which I'm still pounding, by the way. I can't get away from it. I'm so back into the hair metal.

25:50It's really funny. That's awesome. What was it? Keep on walking that road and I'll follow. and if a mirror should break. Superstitious. That was Europe? Yeah, that was Europe. That was another big song besides Final Countdown. Okay. Well, so Scream of Anger. It's a great song. Okay. Scream of Anger is even better. It's like actual metal tinge. Oh, yeah, yeah, yeah. You just made me think of Europe. They're definitely not screamers. They had voices of angels. They did. Obviously Scream and Fear, which is kind of one of the things we've been talking about. screaming and pain. Yikes. That's something that I have never experienced.

26:31I've felt great deals of physical pain, but I'm very internal. I kind of go inward. But I've been to emergency rooms and a screamer in an emergency room is a very unsettling situation. Yeah, for sure. The one I always associate with that is Tom Berenger telling that guy who got shot in the gut in Platoon to eat the pain. uh yeah that's right that guy was definitely screaming in pain yeah yeah he put his hand over his mouth and it was that junior yeah so uh there's also this one's great uh scream of extreme joy yeah like at a concert maybe sure that's one or if you uh watch the simpsons and go back and watch i think the murder house episode where marge is a real estate agent selling a murder house to Ned Flanders, you hear a terrible scream, and it turns out it's Ned Flanders screaming in joy because there's purple drapes in the house.