We are very vocal about this episode, and that’s because it’s all about voices. We look into how our bodies produce sound and talk to a voice recognition expert. And we find out what’s happening when helium enters the equation. Plus, humans don’t have the voice market cornered -- what about other animals? We’ll drop in on a few creatures and find out how they make sounds too.
All that plus a brand new Mystery Sound and berry delicious Moment of Um.
Spoiler alert: For a video related to our mystery sound click here. And for more information click here.
More about how whales make sound here and here:
Educators - Lesson Plan for Brains On! - Voices: How do we make sound? (Right Click to Download)
Audio Transcript
Download transcript (PDF)
ISA: You're listening to Brains On where we're serious about being curious.
SPEAKER 1: Brains On is supported in part by a grant from the National Science Foundation.
ISA: Hello. I'm Isa. Nice to meet you. Hello. I'm Isa. Pass the soy sauce.
MOLLY BLOOM: Hey, Isa. Um, what are you doing?
ISA: I'm trying to figure out what I would sound like when I'm older. Maybe like this? I'm Isa. I'm 37, and I work in sales.
MOLLY BLOOM: [CHUCKLES] Um, hmm, I know something we could try. Hold on. Hold on. Ah, here it is, the kind-of-creepy voice manipulator.
ISA: Why is it kind of creepy?
MOLLY BLOOM: Because it can make me sound like this.
[ELECTRONIC WHOOSHING]
(DEEP VOICE) Hi. I'm Molly, and I like to bench press refrigerators.
ISA: Do me next.
[TRANSITION SOUND]
(DEEP VOICE) This is Isa, and I wrestle bears for a living. But the bears and I are friends.
MOLLY BLOOM: We can also go high. Check it out. [CLEARS THROAT]
(HIGH VOICE) I'm Molly. I'm an elf, and here's my elf song. Doo, doo, doo doo. I am an elf, and I like to dance. Doo, doo, doo doo. Doo, doo, doo doo.
[TRANSITION SOUND]
ISA: (HIGH VOICE) Tiny Isa reporting for duty. I ride a mouse to school, and I sleep in a shoe box.
MOLLY BLOOM: See? Fun but kind of creepy. Let's keep it with us just in case we need it later in the show. Speaking of which--
[TRANSITION SOUND]
(HIGH VOICE) Start the theme song.
[TRANSITION SOUND]
(LOW VOICE) And keep on listening.
[THEME MUSIC]
This is Brains On from American Public Media. I'm Molly Bloom. And my co-host today is 11-year-old Isa from Nyack, New York. Hi. Isa.
ISA: Hi, Molly.
MOLLY BLOOM: Today we're talking about talking, specifically our voices. Isa, you got us thinking about this when you sent us a choir of questions. Do you remember all of the questions about voices you had?
ISA: Yeah.
MOLLY BLOOM: Can you tell us a couple of them?
ISA: Um, I wondered how people's voices sounded different and how animals sound different too from people. So many questions really.
MOLLY BLOOM: [LAUGHS] That's great. We like when people have a lot of questions. Well, you are not the only one interested in voices. We've heard from a lot of listeners.
[MUSIC PLAYING]
JACKSON: I'm Jackson from Reno, Nevada. And my question is, how does your voice box make you speak?
BEN: My name is Ben. I'm from Ohio. And I want to know why boys' and girls' voices are different.
ANSLEY 1: My name is Ansley from Stuttgart, Germany. And my question is why do our voices change as we get older?
[? MORLEY: ?] My name is [? Morley. ?]
ANSLEY 2: And my name is [? Ansley. ?] And we are from Saskatoon, Canada.
MORLEY: Our question is--
BOTH: When we talk, how does the sound of our voice get made?
LIBBY: Hi. My name is Libby from Nederland, Colorado. Why are people's voices different? Bye!
[VOCALIZING]
ISA: Wow that's a volcano of voice questions.
MOLLY BLOOM: Indeed. Let's start with the basics. Here to help do that is Amee Shah. She's a speech and voice expert and professor at Stockton University.
AMEE SHAH: The voice actually starts in our lungs, believe it or not. [BREATHES IN AND OUT]
So the airflow that's sent out from the lungs is then going to this area called the larynx. It's also called the voice box. And in that larynx are tiny, tiny, little flaps called vocal folds, and they come close and move apart. They're like curtains. They come together and go apart.
[VIBRATING]
They're like gatekeepers, so air coming from the lungs is kind of going through this gate. And these vocal folds vibrate, close and open fast, really fast like 500 times in a second.
[VIBRATING FASTER]
That then produces our voice.
[VOCALIZING]
MOLLY BLOOM: So the air from our lungs reaches our vocal cords. The cords can stop the air or let it pass. When it passes, the air vibrates these little pink gates in the back of our throat, and that makes a sound. But Amee says it's still not a voice.
AMEE SHAH: Yeah. It sounds like a buzz at that point, like, doesn't really have the thing that we recognize as voice. It could just be like a buzzing from a machine.
MOLLY BLOOM: So try it. Try it, Isa, with me. Open your mouth wide and talk, but don't use your jaw, or your tongue, or anything else. Just open your mouth wide and try to say something.
ISA: Hello. (STRUGGLING) He-- oh-- heh oh. It's really hard.
MOLLY BLOOM: Yeah? [LAUGHS] It's really hard. It's really hard. Let me try. [MUMBLES] Yeah. It's kind of like when your dentist asks you a question while they're doing stuff in your mouth, and you're like, I ha, ha, ha, ha.
ISA: Yeah. [LAUGHS]
MOLLY BLOOM: So Amee says those sounds from your voice box are manipulated as they move up your throat and out of your mouth. Your tongue, your jaw, even the shape of your nasal cavities change that sound to make it unique.
AMEE SHAH: And all those different channeling creates like this filtering. And then that gives rise to these unique consonants and vowels, like different sounds like puh, and tuh and shuh. And then we also get vowels like ah and ee. And then some nasal sounds like nnn, n-nuh. And all that then also has its unique pitch and loudness and quality. And then that's what we then hear as the human recognizable voice.
ISA: OK so that explains how we get our voice. But what makes some voices high and other voices deep?
MOLLY BLOOM: Excellent question. We call how high or low of a voice is its pitch. And again, this starts with your vocal folds.
AMEE SHAH: The thinner they are, they're going to move faster. That's why for children, they move really fast. And then for men-- it is related to body size. So for men, it's a little heavier, and that's why male pitches are slower.
ISA: Oh! So smaller vocal cords can vibrate faster?
MOLLY BLOOM: Yeah. Isn't that cool? And the faster the vocal chords vibrate, the higher the pitch. It's sort of like a guitar.
[GUITAR STRUMS SLOWLY]
Have you ever played a guitar before, Isa?
ISA: Once, but I haven't practiced it.
MOLLY BLOOM: [LAUGHS] So, well, you know on the guitar, the smallest string is on the bottom, and it's thinner than the others. And when you pluck it--
[HIGH STRUM]
--it's a nice high note. And at the top of the guitar is really a thick, beefy string. And that sounds like this.
[LOW STRUM]
It's low. So do you hear that difference?
ISA: Yeah.
[ELECTRIC GUITAR]
MOLLY BLOOM: So as you grow up, your vocal cords are going to get bigger too. And that's what's going to make your voice deeper. And other things affect pitch too, like how much mass there is in your body, and therefore, the mass of your vocal folds. Grown men are on average larger and heavier than grown women. They also have these lumps in their throat called an Adam's apple. Have you seen that before?
ISA: Yeah, I've seen that before. My dad has one.
MOLLY BLOOM: Yeah, exactly. So that adds mass, and it lowers the pitch of their voice even more. The same thing happens when you have a cold. Your head is full of snot, and that adds mass, and that lowers your pitch too.
ISA: Wait. What do you mean by snot?
MOLLY BLOOM: Yeah. So, like, you know when you have a cold?
ISA: Yeah.
MOLLY BLOOM: And your nose is full of mucus. So that mucus actually goes up pretty far into your nasal cavity. And so that actually adds mass to your head.
ISA: Whoa.
MOLLY BLOOM: And that makes your voice sound lower.
ISA: Wow, that's pretty crazy.
MOLLY BLOOM: Yeah. And you know, even the way you stand, your posture can affect your voice. And your voice changes. I'm sure you've noticed a lot over your life.
ISA: Yeah.
MOLLY BLOOM: When you were little, how did your voice sound compared to the way it sounds now?
ISA: It sounded very, very pitchy. [CHUCKLES]
MOLLY BLOOM: Yeah, like super high? Do you want to hear what I sounded like when I was two years old?
ISA: Yeah. Sure!
TWO-YEAR-OLD MOLLY: Oh. Hear a cat? Meow. Ba-bye!
MOLLY BLOOM: And here's me at eight years old.
EIGHT-YEAR-OLD MOLLY: And I'm going to come towards nursery school because that's the baby's birthday. I'm going to help out and pass out the cupcakes and stuff.
MOLLY BLOOM: And then 18.
18-YEAR-OLD MOLLY: And so the first song I'm going to play for you is a song called Jazz Lips. And that's going to be followed by Lonesome Blues. And these are both songs that Lil wrote and arranged and recorded with the Hot Seven. Here you go.
MOLLY BLOOM: Yep, that is a clip from my college radio show. My voice will continue to change as I get older. I'm done growing, but other things happen to your body as you age too. So what do you think might happen to your body that could change the sound of your voice?
ISA: Hmm. Maybe how tall I am.
MOLLY BLOOM: So when you go from being a kid to an adult, your voice box actually moves lower in your throat. And it becomes much larger, and that makes your voice deeper.
ISA: Oh.
MOLLY BLOOM: Yeah. And then when you become an adult, your voice is still not done changing. So someone who's, like, in their 80s, what does their voice sound like compared to someone in their-- who's like a teenager?
ISA: It sounds deeper and more grumbly. [GIGGLES]
MOLLY BLOOM: Yeah it is like grumbly. It's kind of like creaky or like raspy, maybe not as quite as strong.
ISA: Yeah.
MOLLY BLOOM: And that's because as you get older, you actually lose flexibility. And this makes it harder for the vocal cords to move in the same way. So the muscles in your larynx itself, they might not actually be as strong. And then there are changes to the rest of the body. So remember how your whole body affects the way your voice sounds? So your torso, when you get older, actually becomes a little smaller. And your lungs can become a little smaller too, and they get less flexible.
So just like older people may have trouble walking as well as they used to-- they're a little stiffer, a little slower-- the same thing happens to their voices too. Does that make sense to you?
ISA: Yeah, that makes a lot of sense. And it's very interesting.
MOLLY BLOOM: Yeah, it is. So, like, your voice is made by your body. And as your body changes, your voice changes too. So what about the way the voice works surprises you, Isa?
ISA: Hmm. What really surprises me is like how big your head is and the snot.
[BOTH LAUGH]
MOLLY BLOOM: I know. That's pretty amazing. Yeah, so next time, you're just at home, trying to sing or play around, you could try hunching over a lot. Like right now, I'm hunching over a lot. You hear how my voice is a little different? And now I'm standing up really straight, and my voice is a little different. So you can try moving your body in different ways and seeing how that changes the way your voice sounds.
ISA: That'll be fun.
MOLLY BLOOM: Yeah.
[VOCALIZING]
OK. So Isa, you had a question about the way animals are able to make sounds.
ISA: Yeah.
[ANIMAL SOUNDS]
MOLLY BLOOM: Um, what is that noise?
ISA: I don't know. It sounds sort of sick?
[ANIMAL SOUNDS]
MOLLY BLOOM: Wait. Marc?
MARC SANCHEZ: Oh. Hey. What's up, Molly? Hi, Isa.
ISA: Hi.
MOLLY BLOOM: Are you OK Mark Sanchez?
MARC SANCHEZ: Sure, sure, sure. I'm just trying to perfect my imitation of the male koala's mating call.
ISA: Let me stop you right there. At best, that is straight up weird.
MARC SANCHEZ: OK, OK. I'll give you that. But did you know that koalas have two sets of vocal cords?
MOLLY BLOOM: What?
ISA: That's crazy.
MARC SANCHEZ: Yeah. Scientists were puzzled at how this small of an animal could make such a deep sound. Here, take a listen.
[KOALA SOUNDS]
Researchers made a breakthrough discovery in 2017 when they found that koalas have a second, larger set of vocal cords. As far as we know, koalas are the only creatures that have a second set of vocal cords like this.
ISA: Cool!
MARC SANCHEZ: I know, right? Some animals like koalas and us have a larynx and vocal cords, but there are other animals that don't have the same body makeup. Nevertheless, these animals have evolved and invented all sorts of ways to make sounds and communicate. The list of animal noisemakers is long, but I'm prepared to stay here all day and read them to you. What do you say?
MOLLY BLOOM: How about just giving us a few examples?
MARC SANCHEZ: OK. OK, I got it. This wolf and I will abide.
[WOLF HOWLS]
Wolves, by the way, mammals with a larynx and vocal cords just like us. Now if we focus our ears under the sea, we can hear entirely different sounds from our mammalian cousins.
[WHALE MOANS]
That crooner is a humpback whale. Usually, this kind of song is made by a solitary male humpback. And researchers think these sounds might be a way of attracting females, kind of like our koala pal. Females make sounds too, but they're mainly signal calls letting their family know where they are or where food might be located. How a whale makes this sound is still a mystery.
Humpback whales have a larynx with vocal folds. But they also have something we don't. It's called the laryngeal sac. And it's this extra space at the end of the nasal passage that stores air. Scientists also think this sac plays a part in producing sound, but they're not quite sure how. There are also a few other parts that might help humpbacks make their sounds. Those vocal folds in the larynx, those could operate just like ours. And they also have a set of lip-like flaps a little further up from the vocal folds. And even further up from that, there's more flappy tissue that looks like it could kind of clap together and vibrate to make sound too.
[FROGS CROAKING]
Back on land-- sort of. This is our amphibian pal, the bullfrog. As with most species of frogs, only males make a sound. And by now, I'll bet you can guess why-- the ladies. You know that big puffy sac, that kind of balloon-looking thing you see under a frog's mouth? Well, frogs make sound by rapidly moving air back and forth from the lungs to that sac without exhaling. And that motion opens and closes the vocal cords, making a sound.
[FROGS CROAKING]
And to amplify that sound, bullfrogs especially use something called the tympanic membrane. If you look at them, you'll see kind of a circular patch of skin behind their eyes. That's the tympanic membrane. And it kind of acts like a drum. When they make their bullfrog sound, this tympanic membrane vibrates and sends sound waves out.
[FROGS CROAKING]
And now the moment you've been waiting for, the musical masters of the animal kingdom-- birds. That's right. Our avian buddies can tweet, squawk, and sing like no other. And they owe it all to a special vocal organ that is unique to birds. It's called the syrinx. Our vocal cords are located up in the larynx, but a bird's syrinx is located lower, right where the air tube goes into the lungs. The syrinx has two sets of tissues that a bird can vibrate to make sound. In some birds like the thrush here--
[THRUSH TWEETS]
--they can control each set of sounds independently. That means they can make two different notes at the same time. I'm not that fluent in bird, but I'm pretty sure that thrush is saying, ha-ha! Take that you simple-voiced human.
MOLLY BLOOM: Wow, Marc. Animals are making sounds in so many different ways.
MARC SANCHEZ: Yeah, especially my marsupial pal.
ISA: Oh no.
[MARC'S KOALA SOUNDS]
MARC SANCHEZ: The koala.
MOLLY BLOOM: Thanks, Marc. [LAUGHS]
SINGERS: (SINGING) Ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba. Brains On. Whoa, whoa. Woo, woo.
MOLLY BLOOM: Is there something your voice is itching to say to us?
ISA: Maybe a question?
MOLLY BLOOM: Or do you have a mystery sound or drawing you'd like to send?
ISA: It's easy.
MOLLY BLOOM: Just go to brainson.org/contact. That's how we got this juicy question from Jude and Junie.
ISA: Well, let's hear it.
JUNIE: Hi. My name is Junie.
JUDE: And my name's Jude. Our question is, how do berries and other fruits get their colors?
ISA: We'll answer that in our Moment of Um. Stick around.
MOLLY BLOOM: Plus, we'll shout out the latest crew to join the Brains Honor Roll. And Isa, we're asking for our listeners to help us by writing a letter to the planet Earth. We're working on an episode all about how cool our planet is. And we want to know what your short and sweet letter to Earth would say. So Isa, what would you say to planet Earth in a letter?
ISA: Hmm. Thank you, planet Earth, for taking care of us. Without you, we wouldn't have food, water, supplies, or even a place to live. And thank you for-- if without you, we would have been floating in space--
MOLLY BLOOM: [LAUGHS]
ISA: --without any helmet.
MOLLY BLOOM: [LAUGHS] True. Planet Earth is very important. Listeners, you can send your letter to us by heading to brainson.org/contact.
[DOORBELL RINGS]
ISA: Hey, look who's here.
MOLLY BLOOM: It's Joy Dolo, host of Forever Ago.
JOY DOLO: Hello.
MOLLY BLOOM: She's going to give us a sneak peek of this week's episode of Forever Ago.
JOY DOLO: Yep. It's our brand new history show that dives deep into the history of a different thing every week.
MOLLY BLOOM: And this week, it's clocks.
JOY DOLO: Speaking of which, do you have a favorite time of day, Molly?
MOLLY BLOOM: Hmm. It's a really good question. I would have to say mid-morning because I finally feel awake, and I'm not too tired from the rest of the day, and I can just go.
JOY DOLO: You just chug that coffee.
MOLLY BLOOM: For like a couple of hours.
JOY DOLO: Yeah.
[BOTH LAUGH]
MOLLY BLOOM: Do you have a favorite time?
JOY DOLO: Yes. 6:30, hands down. Get it?
MOLLY BLOOM: Oh!
JOY DOLO: Hands down.
MOLLY BLOOM: I got it. I got there. I got there.
JOY DOLO: It's a good time. All right, now it's time for a sneak peek of the episode.
Communities could differ from each other by odd minutes and seconds. There was Washington, DC time. There was Philadelphia time. There was Boston time. That became very confusing for anybody who wanted to ride a train.
ANNOUNCER: This is the 12:00 PM train.
WOMAN 1: Wait. My clock says it's 12:02 PM.
WOMAN 2: And my clock says it's 12:07.
WOMAN 3: Mine says 11:15 AM. Wait!
[TRAIN WHISTLES]
[? MOLLY BLOOM: ?] It became so much of a problem, there was this big meeting in Chicago organized by the railroad companies-- the 1883 General Time Convention.
[STRIKING GAVEL]
WOMAN 4: We hereby propose a standard time.
MAN 1: To unite trains across the country.
WOMAN 5: The general public is going to love this.
MAN 2: They'll throw a parade in our honor.
[? MOLLY BLOOM: ?] Which is not exactly what happened.
WOMAN 6: Wait, you want me to do what with my watch?
WOMAN 7: I can't just turn back time like that.
[MUSIC PLAYING]
MOLLY BLOOM: You can find Forever Ago and subscribe on Apple Podcasts, Stitcher, or wherever you listen.
JOY DOLO: Episodes come out every Thursday. And if you like the show, leave us a review.
MOLLY BLOOM: I already did.
JOY DOLO: Oh, you're the best. Thanks Molly.
MOLLY BLOOM: Thanks, Joy. Bye.
JOY DOLO: Bye.
ISA: Be sure to subscribe to Forever Ago, and keep on listening.
MOLLY BLOOM: You are listening to Brains On. I'm Molly.
ISA: And I'm Isa.
MOLLY BLOOM: Today--
[TRANSITION SOUND]
--we're exploring voices.
[TRANSITION SOUND]
Yeah.
ISA: What's up next?
MOLLY BLOOM: (HUSKY VOICE) Well, it's time. Hang on a sec.
(CLEAR VOICE) It's time for the mystery sound.
SPEAKER 2: (WHISPERS) Mystery sound.
MOLLY BLOOM: Here it is.
[MYSTERY SOUND]
OK. So Isa, what is your guess?
ISA: Maybe, like, a huge flute? Do you know those sticks?
MOLLY BLOOM: Oh, like a didgeridoo?
ISA: Yeah. Maybe it's a didgeridoo?
MOLLY BLOOM: Excellent guess. We're going to be back with the answer in just a bit. But first, there's another voice question we get a lot.
ISA: It has to do with an element called helium.
EMMA: Hi. I'm Emma from Shreveport, Louisiana.
JEAN: My name is Jean.
OLIVIA: My name is Olivia.
EMMA: Why does helium make your voice have a really, really high pitch?
OLIVIA: When you breathe in helium from a balloon, why does it change your voice?
MOLLY BLOOM: Have you ever done this, Isa? Have you ever inhaled helium?
ISA: Yes. I have.
MOLLY BLOOM: And what is it-- what does it make your voice sound like?
ISA: Really squeaky. But I suggest not to do it because I fainted.
MOLLY BLOOM: You did?
ISA: Yeah.
MOLLY BLOOM: Oh my goodness. Well, yes, this is a good thing that we should be talking about because when you're breathing in helium, that means you're not breathing in oxygen. And as we all know, we need oxygen to live. So inhaling helium is probably not the best idea.
ISA: Yeah. When you Inhale helium, is it doing something to your vocal cords?
MOLLY BLOOM: Actually, you know, it doesn't. It's just changing your voice by changing the medium that the sound travels through. So your voice isn't actually getting higher, it's just the quality of the sound that changes. The pitch isn't changing, it just kind of sounds more quacky. So Isa, when you think of the word wave, what do you think of?
ISA: Like an ocean, like the waves.
MOLLY BLOOM: Yeah, exactly. I think that's what a lot of people think of. And in that particular ocean wave, the wave is an up and down motion. And the medium that that's moving through is water. And sound travels in waves too, and the medium that sound travels through is air. So when I say excuse me--
[CHORUS OF EXCUSE MES]
--I'm sending air out of my mouth, and the molecules in the air vibrate, actually hitting against each other, bumping down the line, creating a wave of sound that then reaches your ear.
ISA: Wow.
MOLLY BLOOM: Yeah, isn't that crazy?
ISA: Yeah.
MOLLY BLOOM: So whenever you're talking, you can picture these little air molecules just flying out of your mouth and hitting each other.
ISA: That's really cool.
MOLLY BLOOM: So when the sound wave created by your voice is moving through helium, it's actually able to move faster than it does through normal air because helium is much, much lighter than the air we usually breathe. And this causes the higher part of your voice to become more amplified than the lower parts of your voice, making you sound kind of like a duck.
ISA: Really?
MOLLY BLOOM: Yeah. So since it's not a great idea to inhale helium, maybe we can just go back to using our kind-of-creepy voice manipulator in the future.
ISA: Well, why wait till the future?
[TRANSITION SOUND]
MOLLY BLOOM: (FAST) You can use it to change the speed too. See? I'm so fast. You'll never catch me.
[TRANSITION SOUND]
ISA: (SLOW) If I talk this slow, it will take forever to-- nah, stick with my normal voice for now.
MOLLY BLOOM: Not even opera singer setting?
[OPERATIC SINGING]
[COUGHS]
You know, Isa? In the future, we might do a lot more with our voices.
ISA: Like paint a picture? Or communicate with plants? Or scream at our phones to charge them? Ha! It's charged.
MOLLY BLOOM: Well, all of that would be really cool. But I was thinking more about computers that respond to voices.
ISA: Oh, like when I say, hey, computer, play me a song by Beyonce.
MOLLY BLOOM: Exactly. Or when I say, hey, smart speaker, how many people have been to the moon? Those programs rely on voice recognition technology, which is a growing field. Here to answer all our voice recognition questions is Mounya Elhilali.
ISA: She's an electrical and computer engineer at Johns Hopkins University. Welcome, Mounya.
MOUNYA ELHILALI: Hi.
ISA: How does voice recognition work? How are computers able to do that?
MOUNYA ELHILALI: So the way voice works, it's basically when we talk, it's like we're pushing air through-- as we open our mouth, we're pushing air through our lungs and our mouth. And the air travels to, let's say if you're talking to another person, those little air waves go inside a person's ear and push a little drum inside our ear called an eardrum, all the way at the end of your ear canal. And so those movements of the air as I'm talking to you right now make your eardrum move a little bit.
And so computers work in a similar way. They sort of track these little movements of air. So when we record the sound, the voice, we're recording these changes in basically the air pressure that goes up and down. So as I'm saying-- if I say ah, ee, oh, ooh, I'm changing how much I push the air molecules. And we're talking about very fast movement, not very slow things and very small.
And so the computers do the same thing. They track these changes, and they look at how they vary. And then they learn basically that certain changes mean certain sounds, certain words, certain letters of the alphabet. And that's how they basically recognize what a voice is saying.
ISA: Oh, that's cool. I didn't think of it like that.
MOLLY BLOOM: So Mounya, how does the computer know what is a voice and what is just like me moving dishes or something in the background?
MOUNYA ELHILALI: The difference between the sound that is coming out of a person's mouth-- that would be our voice and our speech-- versus, for example, if I am clapping right now is just a different pattern of vibration. And so the computers learned that certain patterns are not coming out of a human's voice while human voice has very unique patterns.
MOLLY BLOOM: So how do you teach the computer to recognize these different patterns?
MOUNYA ELHILALI: At a high level, it's basically learning something like templates. So you give it many examples, and you say-- if you want to recognize, let's say, the sound E, then this is what Es looks like. And you give it many examples of E because we all say E slightly differently. Even the same person, when they say E three times, they would say it slightly differently.
And then over time, it learns that all these kinds of patterns, it tries to find what is common among all of the different ways we all say E. And it learns that when it sees those common patterns, then it knows that that's an E. And you do the same thing with all kinds of sounds. So if you're interested in human speech, let's say in English, then you teach it all the possible sounds that come from the English.
You can also teach it patterns of words. And then you can just give it many examples, in a way, similar to how babies start learning to speak. You know, you talk to them, and you give them the example. This is how to produce that sound, and this is what that sound means. But it has to hear the examples over time, and then it learns that.
ISA: Thank you for answering our questions today, Mounya.
MOUNYA ELHILALI: You're very welcome.
[MUSIC PLAYING]
MOLLY BLOOM: Well, before my voice gives out, we need to get back to that mystery sound. Here it is one more time.
[MYSTERY SOUND]
Any new thoughts?
ISA: Hmm, no.
MOLLY BLOOM: So maybe sticking with that didgeridoo or someone just doing something?
ISA: Yeah.
MOLLY BLOOM: [CHUCKLES] OK. Well, here is the answer.
STEVE SKLAR: I'm Steve Sklar, and the sound that you just heard is throat-singing style from Tuva or the Republic of Tuva in Siberia.
ISA: Seriously.
[THROAT-SINGING]
MOLLY BLOOM: Steve is a throat-singer from Minneapolis. The people who do throat-singing are able to make multiple notes at the same time. So out of one mouth comes multiple notes.
STEVE SKLAR: Probably close to 30 years ago, I became aware of a family of vocal techniques, styles and techniques, from Central Asia that the Tuvans call khoomei. And that roughly translates to throat-singing. What throat-singers do is they learn to manipulate structures in the larynx like the vocal folds, some small folds above them in the larynx called the ventricular folds. And we narrow down the inside of the larynx very small, and we put tension on the vocal folds.
This has the approximate result, kind of like taking your stereo and turning down the bass and turning up the treble. And then using various manipulations of the throat and the mouth and especially the tongue, sometimes the cheek, jaw position, and the lips, you set up a series of filters, like different parts of the tongue, the lips, et cetera that are up and forward from the throat that allow you to do all these different changes to the sound. They give you the finished styles.
MOLLY BLOOM: For any aspiring Brains On throat-singers, Steve has some advice.
STEVE SKLAR: The first thing you have to do is listen to the music. I sometimes have people come to me saying, I want to learn how to do this.
[THROAT-SINGING]
If you can get to Central Asia and learn with the native singers, that's a really good way to do it. Prepare to spend some time. And if you do this, you can feel like you're part of a very ancient tradition. Learning the techniques well has allowed me to use them kind of like one would use a flute, or a synthesizer, or something else. So for me, it's a means of expression, but I never forget the connection to where it came from.
MOLLY BLOOM: So I want you to try that at home later. Let me know how it goes.
ISA: That's really, that's going to be a lot of fun.
KIDS: B-B-B-Brains On!
ISA: The way your voice sounds is affected by your whole body.
MOLLY BLOOM: It starts with the air you breathe, going through your larynx, and being shaped by your mouth, lips, and tongue.
ISA: And as your body grows and changes, your voice changes too.
MOLLY BLOOM: Animals have evolved to make noise in many different ways.
ISA: Helium emphasizes the high parts of your voice.
MOLLY BLOOM: And it does that because helium is easier for vibrations to move through than the air we normally breathe. But inhaling helium means you're not inhaling oxygen, so it's not a great idea.
ISA: Computers are getting better and better at understanding our voices. It's a little bit creepy.
MOLLY BLOOM: [LAUGHS] That's it for this episode of Brains On.
ISA: Brains On is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: We had production help from Ned Leebrick-Stryker and Jackie Kim and engineering help from Veronica Rodriguez, Dave [? Schmeelk, ?] Johnny Vince Evans, and Bob [? Alt. ?] Many thanks to Molly Finley, Michael Osborn, Ben [? Charlton, ?] Stan Orchard, Jill [? Soha, ?] Joy [? Reidenberg, ?] and Philip [? Clapham. ?]
ISA: There are more than 100 episodes of Brains On, and you can hear all of them by going to our brainson.org.
MOLLY BLOOM: We're a non-profit public radio podcast, and it's your donations that keep this show going.
ISA: You can donate and see our cool thank you gifts at brainson.org/donate.
MOLLY BLOOM: And you can always check out what we're up to on Instagram and Twitter. We're @brains_on.
ISA: Now before we go, it's time for a Moment of Um.
[CHORUS OF UMS]
JUDE: How do berries and other fruits get their colors?
LI TIAN: My name is Li Tian. I'm a professor at University of California at Davis in the plant sciences department. Berries get their colors because they make molecules known as pigments. Pigments can absorb light. So different pigments absorb light at different wavelengths. So the wavelengths of light that are not being absorbed by pigments are the colors that we see.
For example, blueberries, strawberries, and blackberries, they produce anthocyanin pigments. So anthocyanin pigments absorb light that are now in the blue, red, and black regions. There's another group of pigments known as So these are the colors that we see in melons. They have orange colors. Those are known as beta-carotene. So they're also good for us.
Berries have really bright colors because they want to attract animals, including humans to eat them. So because animals and humans, we don't really consume the seeds, so then we can help these berry plants spread the seeds so the seeds can germinate to make the next generation of berries. And that's how berries and fruits get their colors.
[VOCALIZING]
MOLLY BLOOM: Color me pleased as punch to read this list of names. It's the Brains Honor Roll. It's the way we say thank you to the amazing listeners who share their energy and ideas with us
[LISTING HONOR ROLL]
[MUSIC PLAYING]
Well, Isa, we made it to the end. Want to try one more zap?
ISA: Sure.
[TRANSITION SOUND]
(HIGH VOICE) We'll be back soon with more answers to your questions.
[TRANSITION SOUND]
(DEEP VOICE) Thanks for listening.
SPEAKER 1: Brains On is supported in part by a grant from the National Science Foundation.
ISA: Hello. I'm Isa. Nice to meet you. Hello. I'm Isa. Pass the soy sauce.
MOLLY BLOOM: Hey, Isa. Um, what are you doing?
ISA: I'm trying to figure out what I would sound like when I'm older. Maybe like this? I'm Isa. I'm 37, and I work in sales.
MOLLY BLOOM: [CHUCKLES] Um, hmm, I know something we could try. Hold on. Hold on. Ah, here it is, the kind-of-creepy voice manipulator.
ISA: Why is it kind of creepy?
MOLLY BLOOM: Because it can make me sound like this.
[ELECTRONIC WHOOSHING]
(DEEP VOICE) Hi. I'm Molly, and I like to bench press refrigerators.
ISA: Do me next.
[TRANSITION SOUND]
(DEEP VOICE) This is Isa, and I wrestle bears for a living. But the bears and I are friends.
MOLLY BLOOM: We can also go high. Check it out. [CLEARS THROAT]
(HIGH VOICE) I'm Molly. I'm an elf, and here's my elf song. Doo, doo, doo doo. I am an elf, and I like to dance. Doo, doo, doo doo. Doo, doo, doo doo.
[TRANSITION SOUND]
ISA: (HIGH VOICE) Tiny Isa reporting for duty. I ride a mouse to school, and I sleep in a shoe box.
MOLLY BLOOM: See? Fun but kind of creepy. Let's keep it with us just in case we need it later in the show. Speaking of which--
[TRANSITION SOUND]
(HIGH VOICE) Start the theme song.
[TRANSITION SOUND]
(LOW VOICE) And keep on listening.
[THEME MUSIC]
This is Brains On from American Public Media. I'm Molly Bloom. And my co-host today is 11-year-old Isa from Nyack, New York. Hi. Isa.
ISA: Hi, Molly.
MOLLY BLOOM: Today we're talking about talking, specifically our voices. Isa, you got us thinking about this when you sent us a choir of questions. Do you remember all of the questions about voices you had?
ISA: Yeah.
MOLLY BLOOM: Can you tell us a couple of them?
ISA: Um, I wondered how people's voices sounded different and how animals sound different too from people. So many questions really.
MOLLY BLOOM: [LAUGHS] That's great. We like when people have a lot of questions. Well, you are not the only one interested in voices. We've heard from a lot of listeners.
[MUSIC PLAYING]
JACKSON: I'm Jackson from Reno, Nevada. And my question is, how does your voice box make you speak?
BEN: My name is Ben. I'm from Ohio. And I want to know why boys' and girls' voices are different.
ANSLEY 1: My name is Ansley from Stuttgart, Germany. And my question is why do our voices change as we get older?
[? MORLEY: ?] My name is [? Morley. ?]
ANSLEY 2: And my name is [? Ansley. ?] And we are from Saskatoon, Canada.
MORLEY: Our question is--
BOTH: When we talk, how does the sound of our voice get made?
LIBBY: Hi. My name is Libby from Nederland, Colorado. Why are people's voices different? Bye!
[VOCALIZING]
ISA: Wow that's a volcano of voice questions.
MOLLY BLOOM: Indeed. Let's start with the basics. Here to help do that is Amee Shah. She's a speech and voice expert and professor at Stockton University.
AMEE SHAH: The voice actually starts in our lungs, believe it or not. [BREATHES IN AND OUT]
So the airflow that's sent out from the lungs is then going to this area called the larynx. It's also called the voice box. And in that larynx are tiny, tiny, little flaps called vocal folds, and they come close and move apart. They're like curtains. They come together and go apart.
[VIBRATING]
They're like gatekeepers, so air coming from the lungs is kind of going through this gate. And these vocal folds vibrate, close and open fast, really fast like 500 times in a second.
[VIBRATING FASTER]
That then produces our voice.
[VOCALIZING]
MOLLY BLOOM: So the air from our lungs reaches our vocal cords. The cords can stop the air or let it pass. When it passes, the air vibrates these little pink gates in the back of our throat, and that makes a sound. But Amee says it's still not a voice.
AMEE SHAH: Yeah. It sounds like a buzz at that point, like, doesn't really have the thing that we recognize as voice. It could just be like a buzzing from a machine.
MOLLY BLOOM: So try it. Try it, Isa, with me. Open your mouth wide and talk, but don't use your jaw, or your tongue, or anything else. Just open your mouth wide and try to say something.
ISA: Hello. (STRUGGLING) He-- oh-- heh oh. It's really hard.
MOLLY BLOOM: Yeah? [LAUGHS] It's really hard. It's really hard. Let me try. [MUMBLES] Yeah. It's kind of like when your dentist asks you a question while they're doing stuff in your mouth, and you're like, I ha, ha, ha, ha.
ISA: Yeah. [LAUGHS]
MOLLY BLOOM: So Amee says those sounds from your voice box are manipulated as they move up your throat and out of your mouth. Your tongue, your jaw, even the shape of your nasal cavities change that sound to make it unique.
AMEE SHAH: And all those different channeling creates like this filtering. And then that gives rise to these unique consonants and vowels, like different sounds like puh, and tuh and shuh. And then we also get vowels like ah and ee. And then some nasal sounds like nnn, n-nuh. And all that then also has its unique pitch and loudness and quality. And then that's what we then hear as the human recognizable voice.
ISA: OK so that explains how we get our voice. But what makes some voices high and other voices deep?
MOLLY BLOOM: Excellent question. We call how high or low of a voice is its pitch. And again, this starts with your vocal folds.
AMEE SHAH: The thinner they are, they're going to move faster. That's why for children, they move really fast. And then for men-- it is related to body size. So for men, it's a little heavier, and that's why male pitches are slower.
ISA: Oh! So smaller vocal cords can vibrate faster?
MOLLY BLOOM: Yeah. Isn't that cool? And the faster the vocal chords vibrate, the higher the pitch. It's sort of like a guitar.
[GUITAR STRUMS SLOWLY]
Have you ever played a guitar before, Isa?
ISA: Once, but I haven't practiced it.
MOLLY BLOOM: [LAUGHS] So, well, you know on the guitar, the smallest string is on the bottom, and it's thinner than the others. And when you pluck it--
[HIGH STRUM]
--it's a nice high note. And at the top of the guitar is really a thick, beefy string. And that sounds like this.
[LOW STRUM]
It's low. So do you hear that difference?
ISA: Yeah.
[ELECTRIC GUITAR]
MOLLY BLOOM: So as you grow up, your vocal cords are going to get bigger too. And that's what's going to make your voice deeper. And other things affect pitch too, like how much mass there is in your body, and therefore, the mass of your vocal folds. Grown men are on average larger and heavier than grown women. They also have these lumps in their throat called an Adam's apple. Have you seen that before?
ISA: Yeah, I've seen that before. My dad has one.
MOLLY BLOOM: Yeah, exactly. So that adds mass, and it lowers the pitch of their voice even more. The same thing happens when you have a cold. Your head is full of snot, and that adds mass, and that lowers your pitch too.
ISA: Wait. What do you mean by snot?
MOLLY BLOOM: Yeah. So, like, you know when you have a cold?
ISA: Yeah.
MOLLY BLOOM: And your nose is full of mucus. So that mucus actually goes up pretty far into your nasal cavity. And so that actually adds mass to your head.
ISA: Whoa.
MOLLY BLOOM: And that makes your voice sound lower.
ISA: Wow, that's pretty crazy.
MOLLY BLOOM: Yeah. And you know, even the way you stand, your posture can affect your voice. And your voice changes. I'm sure you've noticed a lot over your life.
ISA: Yeah.
MOLLY BLOOM: When you were little, how did your voice sound compared to the way it sounds now?
ISA: It sounded very, very pitchy. [CHUCKLES]
MOLLY BLOOM: Yeah, like super high? Do you want to hear what I sounded like when I was two years old?
ISA: Yeah. Sure!
TWO-YEAR-OLD MOLLY: Oh. Hear a cat? Meow. Ba-bye!
MOLLY BLOOM: And here's me at eight years old.
EIGHT-YEAR-OLD MOLLY: And I'm going to come towards nursery school because that's the baby's birthday. I'm going to help out and pass out the cupcakes and stuff.
MOLLY BLOOM: And then 18.
18-YEAR-OLD MOLLY: And so the first song I'm going to play for you is a song called Jazz Lips. And that's going to be followed by Lonesome Blues. And these are both songs that Lil wrote and arranged and recorded with the Hot Seven. Here you go.
MOLLY BLOOM: Yep, that is a clip from my college radio show. My voice will continue to change as I get older. I'm done growing, but other things happen to your body as you age too. So what do you think might happen to your body that could change the sound of your voice?
ISA: Hmm. Maybe how tall I am.
MOLLY BLOOM: So when you go from being a kid to an adult, your voice box actually moves lower in your throat. And it becomes much larger, and that makes your voice deeper.
ISA: Oh.
MOLLY BLOOM: Yeah. And then when you become an adult, your voice is still not done changing. So someone who's, like, in their 80s, what does their voice sound like compared to someone in their-- who's like a teenager?
ISA: It sounds deeper and more grumbly. [GIGGLES]
MOLLY BLOOM: Yeah it is like grumbly. It's kind of like creaky or like raspy, maybe not as quite as strong.
ISA: Yeah.
MOLLY BLOOM: And that's because as you get older, you actually lose flexibility. And this makes it harder for the vocal cords to move in the same way. So the muscles in your larynx itself, they might not actually be as strong. And then there are changes to the rest of the body. So remember how your whole body affects the way your voice sounds? So your torso, when you get older, actually becomes a little smaller. And your lungs can become a little smaller too, and they get less flexible.
So just like older people may have trouble walking as well as they used to-- they're a little stiffer, a little slower-- the same thing happens to their voices too. Does that make sense to you?
ISA: Yeah, that makes a lot of sense. And it's very interesting.
MOLLY BLOOM: Yeah, it is. So, like, your voice is made by your body. And as your body changes, your voice changes too. So what about the way the voice works surprises you, Isa?
ISA: Hmm. What really surprises me is like how big your head is and the snot.
[BOTH LAUGH]
MOLLY BLOOM: I know. That's pretty amazing. Yeah, so next time, you're just at home, trying to sing or play around, you could try hunching over a lot. Like right now, I'm hunching over a lot. You hear how my voice is a little different? And now I'm standing up really straight, and my voice is a little different. So you can try moving your body in different ways and seeing how that changes the way your voice sounds.
ISA: That'll be fun.
MOLLY BLOOM: Yeah.
[VOCALIZING]
OK. So Isa, you had a question about the way animals are able to make sounds.
ISA: Yeah.
[ANIMAL SOUNDS]
MOLLY BLOOM: Um, what is that noise?
ISA: I don't know. It sounds sort of sick?
[ANIMAL SOUNDS]
MOLLY BLOOM: Wait. Marc?
MARC SANCHEZ: Oh. Hey. What's up, Molly? Hi, Isa.
ISA: Hi.
MOLLY BLOOM: Are you OK Mark Sanchez?
MARC SANCHEZ: Sure, sure, sure. I'm just trying to perfect my imitation of the male koala's mating call.
ISA: Let me stop you right there. At best, that is straight up weird.
MARC SANCHEZ: OK, OK. I'll give you that. But did you know that koalas have two sets of vocal cords?
MOLLY BLOOM: What?
ISA: That's crazy.
MARC SANCHEZ: Yeah. Scientists were puzzled at how this small of an animal could make such a deep sound. Here, take a listen.
[KOALA SOUNDS]
Researchers made a breakthrough discovery in 2017 when they found that koalas have a second, larger set of vocal cords. As far as we know, koalas are the only creatures that have a second set of vocal cords like this.
ISA: Cool!
MARC SANCHEZ: I know, right? Some animals like koalas and us have a larynx and vocal cords, but there are other animals that don't have the same body makeup. Nevertheless, these animals have evolved and invented all sorts of ways to make sounds and communicate. The list of animal noisemakers is long, but I'm prepared to stay here all day and read them to you. What do you say?
MOLLY BLOOM: How about just giving us a few examples?
MARC SANCHEZ: OK. OK, I got it. This wolf and I will abide.
[WOLF HOWLS]
Wolves, by the way, mammals with a larynx and vocal cords just like us. Now if we focus our ears under the sea, we can hear entirely different sounds from our mammalian cousins.
[WHALE MOANS]
That crooner is a humpback whale. Usually, this kind of song is made by a solitary male humpback. And researchers think these sounds might be a way of attracting females, kind of like our koala pal. Females make sounds too, but they're mainly signal calls letting their family know where they are or where food might be located. How a whale makes this sound is still a mystery.
Humpback whales have a larynx with vocal folds. But they also have something we don't. It's called the laryngeal sac. And it's this extra space at the end of the nasal passage that stores air. Scientists also think this sac plays a part in producing sound, but they're not quite sure how. There are also a few other parts that might help humpbacks make their sounds. Those vocal folds in the larynx, those could operate just like ours. And they also have a set of lip-like flaps a little further up from the vocal folds. And even further up from that, there's more flappy tissue that looks like it could kind of clap together and vibrate to make sound too.
[FROGS CROAKING]
Back on land-- sort of. This is our amphibian pal, the bullfrog. As with most species of frogs, only males make a sound. And by now, I'll bet you can guess why-- the ladies. You know that big puffy sac, that kind of balloon-looking thing you see under a frog's mouth? Well, frogs make sound by rapidly moving air back and forth from the lungs to that sac without exhaling. And that motion opens and closes the vocal cords, making a sound.
[FROGS CROAKING]
And to amplify that sound, bullfrogs especially use something called the tympanic membrane. If you look at them, you'll see kind of a circular patch of skin behind their eyes. That's the tympanic membrane. And it kind of acts like a drum. When they make their bullfrog sound, this tympanic membrane vibrates and sends sound waves out.
[FROGS CROAKING]
And now the moment you've been waiting for, the musical masters of the animal kingdom-- birds. That's right. Our avian buddies can tweet, squawk, and sing like no other. And they owe it all to a special vocal organ that is unique to birds. It's called the syrinx. Our vocal cords are located up in the larynx, but a bird's syrinx is located lower, right where the air tube goes into the lungs. The syrinx has two sets of tissues that a bird can vibrate to make sound. In some birds like the thrush here--
[THRUSH TWEETS]
--they can control each set of sounds independently. That means they can make two different notes at the same time. I'm not that fluent in bird, but I'm pretty sure that thrush is saying, ha-ha! Take that you simple-voiced human.
MOLLY BLOOM: Wow, Marc. Animals are making sounds in so many different ways.
MARC SANCHEZ: Yeah, especially my marsupial pal.
ISA: Oh no.
[MARC'S KOALA SOUNDS]
MARC SANCHEZ: The koala.
MOLLY BLOOM: Thanks, Marc. [LAUGHS]
SINGERS: (SINGING) Ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba. Brains On. Whoa, whoa. Woo, woo.
MOLLY BLOOM: Is there something your voice is itching to say to us?
ISA: Maybe a question?
MOLLY BLOOM: Or do you have a mystery sound or drawing you'd like to send?
ISA: It's easy.
MOLLY BLOOM: Just go to brainson.org/contact. That's how we got this juicy question from Jude and Junie.
ISA: Well, let's hear it.
JUNIE: Hi. My name is Junie.
JUDE: And my name's Jude. Our question is, how do berries and other fruits get their colors?
ISA: We'll answer that in our Moment of Um. Stick around.
MOLLY BLOOM: Plus, we'll shout out the latest crew to join the Brains Honor Roll. And Isa, we're asking for our listeners to help us by writing a letter to the planet Earth. We're working on an episode all about how cool our planet is. And we want to know what your short and sweet letter to Earth would say. So Isa, what would you say to planet Earth in a letter?
ISA: Hmm. Thank you, planet Earth, for taking care of us. Without you, we wouldn't have food, water, supplies, or even a place to live. And thank you for-- if without you, we would have been floating in space--
MOLLY BLOOM: [LAUGHS]
ISA: --without any helmet.
MOLLY BLOOM: [LAUGHS] True. Planet Earth is very important. Listeners, you can send your letter to us by heading to brainson.org/contact.
[DOORBELL RINGS]
ISA: Hey, look who's here.
MOLLY BLOOM: It's Joy Dolo, host of Forever Ago.
JOY DOLO: Hello.
MOLLY BLOOM: She's going to give us a sneak peek of this week's episode of Forever Ago.
JOY DOLO: Yep. It's our brand new history show that dives deep into the history of a different thing every week.
MOLLY BLOOM: And this week, it's clocks.
JOY DOLO: Speaking of which, do you have a favorite time of day, Molly?
MOLLY BLOOM: Hmm. It's a really good question. I would have to say mid-morning because I finally feel awake, and I'm not too tired from the rest of the day, and I can just go.
JOY DOLO: You just chug that coffee.
MOLLY BLOOM: For like a couple of hours.
JOY DOLO: Yeah.
[BOTH LAUGH]
MOLLY BLOOM: Do you have a favorite time?
JOY DOLO: Yes. 6:30, hands down. Get it?
MOLLY BLOOM: Oh!
JOY DOLO: Hands down.
MOLLY BLOOM: I got it. I got there. I got there.
JOY DOLO: It's a good time. All right, now it's time for a sneak peek of the episode.
Communities could differ from each other by odd minutes and seconds. There was Washington, DC time. There was Philadelphia time. There was Boston time. That became very confusing for anybody who wanted to ride a train.
ANNOUNCER: This is the 12:00 PM train.
WOMAN 1: Wait. My clock says it's 12:02 PM.
WOMAN 2: And my clock says it's 12:07.
WOMAN 3: Mine says 11:15 AM. Wait!
[TRAIN WHISTLES]
[? MOLLY BLOOM: ?] It became so much of a problem, there was this big meeting in Chicago organized by the railroad companies-- the 1883 General Time Convention.
[STRIKING GAVEL]
WOMAN 4: We hereby propose a standard time.
MAN 1: To unite trains across the country.
WOMAN 5: The general public is going to love this.
MAN 2: They'll throw a parade in our honor.
[? MOLLY BLOOM: ?] Which is not exactly what happened.
WOMAN 6: Wait, you want me to do what with my watch?
WOMAN 7: I can't just turn back time like that.
[MUSIC PLAYING]
MOLLY BLOOM: You can find Forever Ago and subscribe on Apple Podcasts, Stitcher, or wherever you listen.
JOY DOLO: Episodes come out every Thursday. And if you like the show, leave us a review.
MOLLY BLOOM: I already did.
JOY DOLO: Oh, you're the best. Thanks Molly.
MOLLY BLOOM: Thanks, Joy. Bye.
JOY DOLO: Bye.
ISA: Be sure to subscribe to Forever Ago, and keep on listening.
MOLLY BLOOM: You are listening to Brains On. I'm Molly.
ISA: And I'm Isa.
MOLLY BLOOM: Today--
[TRANSITION SOUND]
--we're exploring voices.
[TRANSITION SOUND]
Yeah.
ISA: What's up next?
MOLLY BLOOM: (HUSKY VOICE) Well, it's time. Hang on a sec.
(CLEAR VOICE) It's time for the mystery sound.
SPEAKER 2: (WHISPERS) Mystery sound.
MOLLY BLOOM: Here it is.
[MYSTERY SOUND]
OK. So Isa, what is your guess?
ISA: Maybe, like, a huge flute? Do you know those sticks?
MOLLY BLOOM: Oh, like a didgeridoo?
ISA: Yeah. Maybe it's a didgeridoo?
MOLLY BLOOM: Excellent guess. We're going to be back with the answer in just a bit. But first, there's another voice question we get a lot.
ISA: It has to do with an element called helium.
EMMA: Hi. I'm Emma from Shreveport, Louisiana.
JEAN: My name is Jean.
OLIVIA: My name is Olivia.
EMMA: Why does helium make your voice have a really, really high pitch?
OLIVIA: When you breathe in helium from a balloon, why does it change your voice?
MOLLY BLOOM: Have you ever done this, Isa? Have you ever inhaled helium?
ISA: Yes. I have.
MOLLY BLOOM: And what is it-- what does it make your voice sound like?
ISA: Really squeaky. But I suggest not to do it because I fainted.
MOLLY BLOOM: You did?
ISA: Yeah.
MOLLY BLOOM: Oh my goodness. Well, yes, this is a good thing that we should be talking about because when you're breathing in helium, that means you're not breathing in oxygen. And as we all know, we need oxygen to live. So inhaling helium is probably not the best idea.
ISA: Yeah. When you Inhale helium, is it doing something to your vocal cords?
MOLLY BLOOM: Actually, you know, it doesn't. It's just changing your voice by changing the medium that the sound travels through. So your voice isn't actually getting higher, it's just the quality of the sound that changes. The pitch isn't changing, it just kind of sounds more quacky. So Isa, when you think of the word wave, what do you think of?
ISA: Like an ocean, like the waves.
MOLLY BLOOM: Yeah, exactly. I think that's what a lot of people think of. And in that particular ocean wave, the wave is an up and down motion. And the medium that that's moving through is water. And sound travels in waves too, and the medium that sound travels through is air. So when I say excuse me--
[CHORUS OF EXCUSE MES]
--I'm sending air out of my mouth, and the molecules in the air vibrate, actually hitting against each other, bumping down the line, creating a wave of sound that then reaches your ear.
ISA: Wow.
MOLLY BLOOM: Yeah, isn't that crazy?
ISA: Yeah.
MOLLY BLOOM: So whenever you're talking, you can picture these little air molecules just flying out of your mouth and hitting each other.
ISA: That's really cool.
MOLLY BLOOM: So when the sound wave created by your voice is moving through helium, it's actually able to move faster than it does through normal air because helium is much, much lighter than the air we usually breathe. And this causes the higher part of your voice to become more amplified than the lower parts of your voice, making you sound kind of like a duck.
ISA: Really?
MOLLY BLOOM: Yeah. So since it's not a great idea to inhale helium, maybe we can just go back to using our kind-of-creepy voice manipulator in the future.
ISA: Well, why wait till the future?
[TRANSITION SOUND]
MOLLY BLOOM: (FAST) You can use it to change the speed too. See? I'm so fast. You'll never catch me.
[TRANSITION SOUND]
ISA: (SLOW) If I talk this slow, it will take forever to-- nah, stick with my normal voice for now.
MOLLY BLOOM: Not even opera singer setting?
[OPERATIC SINGING]
[COUGHS]
You know, Isa? In the future, we might do a lot more with our voices.
ISA: Like paint a picture? Or communicate with plants? Or scream at our phones to charge them? Ha! It's charged.
MOLLY BLOOM: Well, all of that would be really cool. But I was thinking more about computers that respond to voices.
ISA: Oh, like when I say, hey, computer, play me a song by Beyonce.
MOLLY BLOOM: Exactly. Or when I say, hey, smart speaker, how many people have been to the moon? Those programs rely on voice recognition technology, which is a growing field. Here to answer all our voice recognition questions is Mounya Elhilali.
ISA: She's an electrical and computer engineer at Johns Hopkins University. Welcome, Mounya.
MOUNYA ELHILALI: Hi.
ISA: How does voice recognition work? How are computers able to do that?
MOUNYA ELHILALI: So the way voice works, it's basically when we talk, it's like we're pushing air through-- as we open our mouth, we're pushing air through our lungs and our mouth. And the air travels to, let's say if you're talking to another person, those little air waves go inside a person's ear and push a little drum inside our ear called an eardrum, all the way at the end of your ear canal. And so those movements of the air as I'm talking to you right now make your eardrum move a little bit.
And so computers work in a similar way. They sort of track these little movements of air. So when we record the sound, the voice, we're recording these changes in basically the air pressure that goes up and down. So as I'm saying-- if I say ah, ee, oh, ooh, I'm changing how much I push the air molecules. And we're talking about very fast movement, not very slow things and very small.
And so the computers do the same thing. They track these changes, and they look at how they vary. And then they learn basically that certain changes mean certain sounds, certain words, certain letters of the alphabet. And that's how they basically recognize what a voice is saying.
ISA: Oh, that's cool. I didn't think of it like that.
MOLLY BLOOM: So Mounya, how does the computer know what is a voice and what is just like me moving dishes or something in the background?
MOUNYA ELHILALI: The difference between the sound that is coming out of a person's mouth-- that would be our voice and our speech-- versus, for example, if I am clapping right now is just a different pattern of vibration. And so the computers learned that certain patterns are not coming out of a human's voice while human voice has very unique patterns.
MOLLY BLOOM: So how do you teach the computer to recognize these different patterns?
MOUNYA ELHILALI: At a high level, it's basically learning something like templates. So you give it many examples, and you say-- if you want to recognize, let's say, the sound E, then this is what Es looks like. And you give it many examples of E because we all say E slightly differently. Even the same person, when they say E three times, they would say it slightly differently.
And then over time, it learns that all these kinds of patterns, it tries to find what is common among all of the different ways we all say E. And it learns that when it sees those common patterns, then it knows that that's an E. And you do the same thing with all kinds of sounds. So if you're interested in human speech, let's say in English, then you teach it all the possible sounds that come from the English.
You can also teach it patterns of words. And then you can just give it many examples, in a way, similar to how babies start learning to speak. You know, you talk to them, and you give them the example. This is how to produce that sound, and this is what that sound means. But it has to hear the examples over time, and then it learns that.
ISA: Thank you for answering our questions today, Mounya.
MOUNYA ELHILALI: You're very welcome.
[MUSIC PLAYING]
MOLLY BLOOM: Well, before my voice gives out, we need to get back to that mystery sound. Here it is one more time.
[MYSTERY SOUND]
Any new thoughts?
ISA: Hmm, no.
MOLLY BLOOM: So maybe sticking with that didgeridoo or someone just doing something?
ISA: Yeah.
MOLLY BLOOM: [CHUCKLES] OK. Well, here is the answer.
STEVE SKLAR: I'm Steve Sklar, and the sound that you just heard is throat-singing style from Tuva or the Republic of Tuva in Siberia.
ISA: Seriously.
[THROAT-SINGING]
MOLLY BLOOM: Steve is a throat-singer from Minneapolis. The people who do throat-singing are able to make multiple notes at the same time. So out of one mouth comes multiple notes.
STEVE SKLAR: Probably close to 30 years ago, I became aware of a family of vocal techniques, styles and techniques, from Central Asia that the Tuvans call khoomei. And that roughly translates to throat-singing. What throat-singers do is they learn to manipulate structures in the larynx like the vocal folds, some small folds above them in the larynx called the ventricular folds. And we narrow down the inside of the larynx very small, and we put tension on the vocal folds.
This has the approximate result, kind of like taking your stereo and turning down the bass and turning up the treble. And then using various manipulations of the throat and the mouth and especially the tongue, sometimes the cheek, jaw position, and the lips, you set up a series of filters, like different parts of the tongue, the lips, et cetera that are up and forward from the throat that allow you to do all these different changes to the sound. They give you the finished styles.
MOLLY BLOOM: For any aspiring Brains On throat-singers, Steve has some advice.
STEVE SKLAR: The first thing you have to do is listen to the music. I sometimes have people come to me saying, I want to learn how to do this.
[THROAT-SINGING]
If you can get to Central Asia and learn with the native singers, that's a really good way to do it. Prepare to spend some time. And if you do this, you can feel like you're part of a very ancient tradition. Learning the techniques well has allowed me to use them kind of like one would use a flute, or a synthesizer, or something else. So for me, it's a means of expression, but I never forget the connection to where it came from.
MOLLY BLOOM: So I want you to try that at home later. Let me know how it goes.
ISA: That's really, that's going to be a lot of fun.
KIDS: B-B-B-Brains On!
ISA: The way your voice sounds is affected by your whole body.
MOLLY BLOOM: It starts with the air you breathe, going through your larynx, and being shaped by your mouth, lips, and tongue.
ISA: And as your body grows and changes, your voice changes too.
MOLLY BLOOM: Animals have evolved to make noise in many different ways.
ISA: Helium emphasizes the high parts of your voice.
MOLLY BLOOM: And it does that because helium is easier for vibrations to move through than the air we normally breathe. But inhaling helium means you're not inhaling oxygen, so it's not a great idea.
ISA: Computers are getting better and better at understanding our voices. It's a little bit creepy.
MOLLY BLOOM: [LAUGHS] That's it for this episode of Brains On.
ISA: Brains On is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: We had production help from Ned Leebrick-Stryker and Jackie Kim and engineering help from Veronica Rodriguez, Dave [? Schmeelk, ?] Johnny Vince Evans, and Bob [? Alt. ?] Many thanks to Molly Finley, Michael Osborn, Ben [? Charlton, ?] Stan Orchard, Jill [? Soha, ?] Joy [? Reidenberg, ?] and Philip [? Clapham. ?]
ISA: There are more than 100 episodes of Brains On, and you can hear all of them by going to our brainson.org.
MOLLY BLOOM: We're a non-profit public radio podcast, and it's your donations that keep this show going.
ISA: You can donate and see our cool thank you gifts at brainson.org/donate.
MOLLY BLOOM: And you can always check out what we're up to on Instagram and Twitter. We're @brains_on.
ISA: Now before we go, it's time for a Moment of Um.
[CHORUS OF UMS]
JUDE: How do berries and other fruits get their colors?
LI TIAN: My name is Li Tian. I'm a professor at University of California at Davis in the plant sciences department. Berries get their colors because they make molecules known as pigments. Pigments can absorb light. So different pigments absorb light at different wavelengths. So the wavelengths of light that are not being absorbed by pigments are the colors that we see.
For example, blueberries, strawberries, and blackberries, they produce anthocyanin pigments. So anthocyanin pigments absorb light that are now in the blue, red, and black regions. There's another group of pigments known as So these are the colors that we see in melons. They have orange colors. Those are known as beta-carotene. So they're also good for us.
Berries have really bright colors because they want to attract animals, including humans to eat them. So because animals and humans, we don't really consume the seeds, so then we can help these berry plants spread the seeds so the seeds can germinate to make the next generation of berries. And that's how berries and fruits get their colors.
[VOCALIZING]
MOLLY BLOOM: Color me pleased as punch to read this list of names. It's the Brains Honor Roll. It's the way we say thank you to the amazing listeners who share their energy and ideas with us
[LISTING HONOR ROLL]
[MUSIC PLAYING]
Well, Isa, we made it to the end. Want to try one more zap?
ISA: Sure.
[TRANSITION SOUND]
(HIGH VOICE) We'll be back soon with more answers to your questions.
[TRANSITION SOUND]
(DEEP VOICE) Thanks for listening.
Transcription services provided by 3Play Media.
