0:00:02 > 0:00:06What might be the first human sound aliens ever hear?
0:00:06 > 0:00:10VARIED TYPES OF LAUGHTER
0:00:11 > 0:00:15It might be the sound of laughter, because laughter is on this record.
0:00:15 > 0:00:19It's called The Sounds Of Earth and the real version is attached to the
0:00:19 > 0:00:24NASA Voyager spacecraft, the most distant man-made object from earth.
0:00:24 > 0:00:27Why would we be trying to greet aliens with laughter?
0:00:27 > 0:00:30Well, because laughter is one of mankind's most important sound
0:00:30 > 0:00:32communications.
0:00:32 > 0:00:35Humans and animals are constantly sending messages to each other in
0:00:35 > 0:00:37different ways.
0:00:37 > 0:00:38In these lectures,
0:00:38 > 0:00:41I'm going to be showing you where this incredible urge to communicate
0:00:41 > 0:00:43comes from, and why it's essential
0:00:43 > 0:00:46for the survival of so many species on earth.
0:00:46 > 0:00:49Welcome to The Language Of Life.
0:01:03 > 0:01:06APPLAUSE
0:01:15 > 0:01:20Welcome, welcome to the 2017 Royal Institution Christmas Lectures.
0:01:20 > 0:01:23I'm Professor Sophie Scott, and I'm a cognitive neuroscientist.
0:01:23 > 0:01:26I study the human brain and human communication,
0:01:26 > 0:01:28and I've got a message for you,
0:01:28 > 0:01:32from one of my favourite research participants, Doug Collins.
0:01:33 > 0:01:35Hi, Sophie. Hi, everyone.
0:01:35 > 0:01:38I'm Doug and I have the most contagious laugh in the world,
0:01:38 > 0:01:40as most people have said.
0:01:40 > 0:01:43HE LAUGHS
0:01:48 > 0:01:50Laughter's a very basic kind of communication.
0:01:50 > 0:01:52It's actually sending a very important message.
0:01:52 > 0:01:54It's sending a message to people that you're happy,
0:01:54 > 0:01:56you like the people that you're with,
0:01:56 > 0:01:59you feel friendly towards them.
0:01:59 > 0:02:03It's also, if you noticed there, a very funny kind of sound.
0:02:03 > 0:02:07In fact, laughter is a lot more like an animal call than it is like the
0:02:07 > 0:02:08speech we normally do.
0:02:09 > 0:02:11And in fact, there's a reason for that.
0:02:11 > 0:02:15We are not the only animal that laughs,
0:02:15 > 0:02:18that sends messages with their laughter, in fact.
0:02:18 > 0:02:21Shall we have a go at making some animals laugh right now?
0:02:21 > 0:02:24- AUDIENCE:- Yes.- Definitely. I am delighted to introduce to you -
0:02:24 > 0:02:28you have to use tiny little non-frightening finger claps -
0:02:28 > 0:02:32to introduce you to India Woods and her rat, called Mould.
0:02:32 > 0:02:33Big claps.
0:02:34 > 0:02:36Hello. Hello, India.
0:02:36 > 0:02:39Hello, Mould. I am so excited to meet you.
0:02:39 > 0:02:41- Fantastic.- There we go.
0:02:41 > 0:02:43Does Mould laugh ever?
0:02:43 > 0:02:44He makes some noises.
0:02:44 > 0:02:48Excellent. What do you do normally to make Mould make a noise?
0:02:48 > 0:02:50- You tickle him.- Oh.
0:02:50 > 0:02:53OK. Where's the best place to tickle a rat?
0:02:53 > 0:02:55Where you tickle a person.
0:02:55 > 0:02:56His armpit, on his back.
0:02:56 > 0:02:59There we go. Now I don't know about you,
0:02:59 > 0:03:02I don't normally feel at my most ticklish
0:03:02 > 0:03:06when I'm being watched by about 250 complete strange people
0:03:06 > 0:03:08and I've been placed on a little podium.
0:03:08 > 0:03:10So I think what we might be doing is, we might
0:03:10 > 0:03:13be making it slightly hard for Mould to feel like having a laugh.
0:03:13 > 0:03:17I think we have some examples of his laughter from earlier today.
0:03:17 > 0:03:18- Yes.- Can we hear that?
0:03:18 > 0:03:22CHIRPY SQUEAKING
0:03:25 > 0:03:27You can hear these little chirrupy chirps.
0:03:29 > 0:03:33Now that actually is the sound that he's making when he laughs.
0:03:33 > 0:03:36We know it's something to do with laughter because rats, just like us,
0:03:36 > 0:03:39they laugh when they're tickled. They laugh when they're playing,
0:03:39 > 0:03:41they laugh when they want you to play with them.
0:03:41 > 0:03:45So it's actually a very important communication sound for rats and for
0:03:45 > 0:03:48humans. Thank you very much.
0:03:48 > 0:03:50- Thank you.- Bye-bye, sweetie.
0:03:50 > 0:03:57We share a common ancestor with rats going back 65 million years.
0:03:57 > 0:04:00So it's possible that laughter really is
0:04:00 > 0:04:03a very old communication sound for mammals.
0:04:03 > 0:04:07It's possibly certainly one of our earliest communication sounds.
0:04:07 > 0:04:11But what would the very first communication sounds have been on earth?
0:04:12 > 0:04:15What would have been the first animals to communicate with sounds?
0:04:15 > 0:04:18Who would they be? Well, to think about that we're going
0:04:18 > 0:04:20to look at these charming specimens.
0:04:20 > 0:04:23These are insects. They're actually crickets.
0:04:24 > 0:04:29500 million years ago, insects crawled on to the earth,
0:04:29 > 0:04:31and they're therefore very good candidates for being the first
0:04:31 > 0:04:35animals to use sound for communication in the air.
0:04:35 > 0:04:38So, if we look closely at these guys,
0:04:38 > 0:04:40we can see they have legs and they have wings.
0:04:40 > 0:04:44I can hear they aren't making a sound, so we are going to play in...
0:04:45 > 0:04:48..an example of what it would sound like.
0:04:48 > 0:04:51CHIRPING
0:04:52 > 0:04:53Can you hear? That chirping sound?
0:04:55 > 0:04:57It's actually a very, very basic communication.
0:04:57 > 0:04:59What they're saying is "I am here."
0:04:59 > 0:05:01"I'm a cricket and I am here."
0:05:01 > 0:05:03It's basically a mating call.
0:05:03 > 0:05:06The most basic sound you could have, really. "I'm right here.
0:05:06 > 0:05:07"Whenever you're ready, I'm here."
0:05:07 > 0:05:10So... And they're making it in this fantastic way.
0:05:10 > 0:05:12It is simply the best word in science.
0:05:12 > 0:05:16They make it via a process called stridulation.
0:05:16 > 0:05:18They are stridulating.
0:05:18 > 0:05:21And what stridulation means is they're rubbing body parts together.
0:05:21 > 0:05:23The way the crickets are doing this is,
0:05:23 > 0:05:25they're actually running their wings together.
0:05:25 > 0:05:30If we look at a close-up image of the base of a cricket's wing,
0:05:30 > 0:05:33you can see it has this very regular notched surface.
0:05:33 > 0:05:35When they rub their wings together,
0:05:35 > 0:05:39you get a very regular sound coming out of that movement.
0:05:39 > 0:05:41There's actually musical instrument that humans use
0:05:41 > 0:05:43that makes a sound in a very similar way.
0:05:43 > 0:05:46I would like to have a volunteer to have a go at playing this for me.
0:05:46 > 0:05:48Can I have you, with the glasses, in the scarf? Thank you very much.
0:05:48 > 0:05:50Thank you very much.
0:05:56 > 0:05:58- Now, what's your name?- Alex.
0:05:58 > 0:05:59Alex, it's lovely to meet you.
0:05:59 > 0:06:03Can I present you with guero? OK.
0:06:03 > 0:06:05How do you think you might get a sound out of that?
0:06:05 > 0:06:07WHISPERS: It's a bit like the crickets.
0:06:09 > 0:06:11Excellent. Go a bit more slowly.
0:06:14 > 0:06:15Fantastic.
0:06:16 > 0:06:18Top guero playing.
0:06:18 > 0:06:21Now you can see there, that, actually,
0:06:21 > 0:06:23the regular notches are giving you regularity in the sound.
0:06:23 > 0:06:26The crickets aren't just making a noise,
0:06:26 > 0:06:29they're making a noise that has some recognisability to it.
0:06:29 > 0:06:30It's got some information in it.
0:06:30 > 0:06:33It's kind of built in to the structure of the way
0:06:33 > 0:06:36it's making the sound at all. Thank you very, very much.
0:06:36 > 0:06:38I'll have the guero back. Thank you, Alex.
0:06:38 > 0:06:40APPLAUSE
0:06:42 > 0:06:44So, Alex was basically stridulating for you there.
0:06:44 > 0:06:47She was rubbing two things together to make a sound,
0:06:47 > 0:06:48but actually, generally,
0:06:48 > 0:06:51whenever you hear a sound, it means something happened,
0:06:51 > 0:06:53there was some kind of action in the world.
0:06:53 > 0:06:55If there aren't any movements,
0:06:55 > 0:06:58if there aren't any actions, there are no sounds.
0:06:58 > 0:07:02And we could see there how the regularity in the shape of the guero
0:07:02 > 0:07:05or the cricket's wing is giving you regularity to the sound.
0:07:05 > 0:07:07That is important for the crickets.
0:07:07 > 0:07:10But how do we hear that as a sound?
0:07:10 > 0:07:13How do we experience that vibration
0:07:13 > 0:07:16as something we can actually perceive?
0:07:16 > 0:07:17Well, to think about that,
0:07:17 > 0:07:21what we need to do is look at a slightly more simple system.
0:07:21 > 0:07:22We are going to look at a tuning fork.
0:07:25 > 0:07:27Now this isn't any old tuning fork.
0:07:27 > 0:07:29This belonged to John Tyndall, who is - was -
0:07:29 > 0:07:32a scientist here at the Royal Institution.
0:07:32 > 0:07:36This is 150 years old, and John Tyndall did some amazing work.
0:07:36 > 0:07:39He discovered why we see the sky as looking blue and how the greenhouse
0:07:39 > 0:07:42effect can lead to global warming.
0:07:42 > 0:07:45What I am going to do is hit one of his 150-year-old tuning forks,
0:07:45 > 0:07:49and hopefully, we should be able to hear a sound.
0:07:49 > 0:07:52MEDIUM-PITCHED DINGING
0:07:54 > 0:07:57Now the sound is being made by movements that tuning fork,
0:07:57 > 0:08:00but I can't really see those movements as they're moving too quickly.
0:08:00 > 0:08:04So, what I'm going to do is turn to a high-speed camera
0:08:04 > 0:08:07and we're going to see if we can slow that down and look at it in more detail.
0:08:07 > 0:08:10To do this, we're going to need more light because the high-speed camera
0:08:10 > 0:08:13needs more light information to get good images.
0:08:14 > 0:08:15Thank you.
0:08:16 > 0:08:18OK. I'm going to hit it again.
0:08:18 > 0:08:21MEDIUM-PITCHED DINGING
0:08:21 > 0:08:23You can see there,
0:08:23 > 0:08:28I'm hitting it and immediately the tines of the fork start to vibrate.
0:08:28 > 0:08:31And that's what's causing the sound to happen.
0:08:31 > 0:08:33That's giving us something we can hear.
0:08:33 > 0:08:39And it's doing that by causing all the air molecules in the atmosphere
0:08:39 > 0:08:41around us to start to vibrate,
0:08:41 > 0:08:45and what this sets up is a chain of movements of these air molecules,
0:08:45 > 0:08:47vibrating back and forth.
0:08:47 > 0:08:52You get waves of air molecules stretching out and being compressed,
0:08:52 > 0:08:55and when it reaches our ears, that's what we hear as a sound.
0:08:55 > 0:08:58It is very hard to imagine that with the air molecules.
0:08:58 > 0:09:02It is easier to imagine with a spring.
0:09:02 > 0:09:05So the air, like this spring, is extremely elastic.
0:09:07 > 0:09:11What I'm going to do is put a single vibration into the spring.
0:09:12 > 0:09:16And you can see how it's being passed along.
0:09:18 > 0:09:20Although any one single coil of the spring
0:09:20 > 0:09:22is not moving very far at all.
0:09:23 > 0:09:28We get that pattern of the waves, of compression, and stretching out.
0:09:28 > 0:09:29Thank you very much.
0:09:30 > 0:09:31Thank you.
0:09:31 > 0:09:34It's easy to see those vibrations in the spring.
0:09:34 > 0:09:38We don't really notice it happening in the air around us.
0:09:38 > 0:09:41But there is an extremely sensitive photographic technique called
0:09:41 > 0:09:46schlieren photography that lets us record the disturbances in the air
0:09:46 > 0:09:48as the sound waves are passing through.
0:09:50 > 0:09:53So, this is somebody about to clap their hands.
0:09:55 > 0:09:59And as their hands contact, look for the sound waves radiating out.
0:09:59 > 0:10:04Did you see that pattern of movement radiating out from the hands?
0:10:04 > 0:10:08It's been slowed right down, but you can see that was coming from the
0:10:08 > 0:10:10source of the sound.
0:10:10 > 0:10:13Now, all sounds are made by movements,
0:10:13 > 0:10:16but how do our bodies pick them up and hear them?
0:10:16 > 0:10:18How do we decode sounds?
0:10:18 > 0:10:21Now, tell me, what organ do you use to hear sounds?
0:10:21 > 0:10:23Point to it.
0:10:23 > 0:10:24Yes, your ears.
0:10:24 > 0:10:28Absolutely. In fact, the bits on the outside that we all just pointed to,
0:10:28 > 0:10:29that's just the outside of your ear.
0:10:29 > 0:10:31That's called the pinna.
0:10:31 > 0:10:33And what that does is it's a funnel
0:10:33 > 0:10:36for pointing all these air vibrations
0:10:36 > 0:10:41down towards the real ear, which is actually located down,
0:10:41 > 0:10:43tucked away inside your head.
0:10:43 > 0:10:46And what this is doing, it's trying to turn the vibrations that are
0:10:46 > 0:10:48sending sound over to you
0:10:48 > 0:10:50into something that the brain can perceive.
0:10:50 > 0:10:54And what the brain wants is the information in an electrical form.
0:10:54 > 0:10:57Your brain deals with electrical signals.
0:10:59 > 0:11:00So how do we turn...
0:11:00 > 0:11:04these vibrations of the air molecules into an electrical signal?
0:11:04 > 0:11:07Well, this is a demonstration of that at work.
0:11:07 > 0:11:11So we have air molecules moving down and it's funnelled in
0:11:11 > 0:11:13by your pinna towards the eardrum.
0:11:13 > 0:11:16And what you have at the eardrum is just like a drum.
0:11:16 > 0:11:20It's vibrating when the air molecules push against it
0:11:20 > 0:11:23and then transmits that pattern of vibration
0:11:23 > 0:11:27through the tiny little bones, the smallest bones in your body.
0:11:27 > 0:11:31And then that is sending a vibration into one end of what's called the
0:11:31 > 0:11:36cochlea. And the cochlea is a fluid-filled tube
0:11:36 > 0:11:39and that fluid starts to move with the vibrations.
0:11:39 > 0:11:42So, it's all still physical movement,
0:11:42 > 0:11:46and in the cochlea, there are these tiny little cells called hair cells.
0:11:46 > 0:11:48And they start to bob up and down.
0:11:48 > 0:11:51And they have small filaments called the hairs.
0:11:51 > 0:11:52When those move...
0:11:52 > 0:11:55When the whole thing bobs up and down like that,
0:11:55 > 0:11:59that is what sends an electrical signal to your brain.
0:11:59 > 0:12:01So, the entire ear is a machine
0:12:01 > 0:12:03for turning the vibrations of the air into
0:12:03 > 0:12:05something your brain can hear as sound.
0:12:05 > 0:12:08And, of course, if anything goes wrong
0:12:08 > 0:12:09with this entire chain of events,
0:12:09 > 0:12:11you'll have a problem with your hearing.
0:12:11 > 0:12:14The ear has moving parts and those moving parts can break.
0:12:16 > 0:12:18So, communication with sound
0:12:18 > 0:12:21is about creating movement of molecules,
0:12:21 > 0:12:26which another creature can pick up, detect and experience as sound.
0:12:27 > 0:12:30However, we're living in quite a noisy world.
0:12:30 > 0:12:34We only tend to notice sounds that we can hear.
0:12:34 > 0:12:37But there are lots and lots of communication sounds we can't hear.
0:12:38 > 0:12:41So, we've got an example here for another tuning fork.
0:12:41 > 0:12:45Now this tuning fork is much larger than the one I showed you before.
0:12:46 > 0:12:51This one will vibrate at a pitch much too low for us to hear.
0:12:52 > 0:12:55So, how do I convince you that something's making a sound
0:12:55 > 0:12:56that you can't hear?
0:12:56 > 0:12:59Well, I suppose I could just ask you to believe me,
0:12:59 > 0:13:01but let's try and do it with a demonstration.
0:13:01 > 0:13:06What we're going to do here is we're going to put sound into the tuning
0:13:06 > 0:13:07fork through this loudspeaker.
0:13:09 > 0:13:12You'll hear the sound at first cos it will still be in a range where we
0:13:12 > 0:13:13can hear sounds.
0:13:13 > 0:13:16And then it will drop down so that we can't really hear it at all.
0:13:16 > 0:13:20But we will start to see the tuning fork itself begin to move.
0:13:22 > 0:13:24OK, you can put your hands over your ears for this.
0:13:24 > 0:13:26Right.
0:13:26 > 0:13:28LOW-PITCHED HUM
0:13:28 > 0:13:30Still hear that? Still hear that?
0:13:31 > 0:13:33PITCH LOWERS Going down.
0:13:34 > 0:13:36PITCH LOWERS AND BECOMES INAUDIBLE
0:13:36 > 0:13:40Now, if you look, you can see the loudspeaker moving.
0:13:40 > 0:13:42There are sounds coming out of that.
0:13:42 > 0:13:44And it's starting to vibrate the tuning fork.
0:13:44 > 0:13:47So there's energy coming out of here we can't hear.
0:13:50 > 0:13:52That's called infra-sound,
0:13:52 > 0:13:55sound that's simply too low for us to be able to detect.
0:13:56 > 0:14:00And infra-sounds can be exploited by animals,
0:14:00 > 0:14:03normally animals much larger than us.
0:14:03 > 0:14:05Animals, in fact, that I'm very fond of.
0:14:05 > 0:14:06Elephants.
0:14:06 > 0:14:11Now, I'm very sorry to say I haven't got an elephant to show you.
0:14:11 > 0:14:13We can't get them in the lift.
0:14:15 > 0:14:17So I went to ZSL, Whipsnade Zoo,
0:14:17 > 0:14:21to meet qualified elephant keeper Ben Abbott and find out more.
0:14:28 > 0:14:32So, the very low-pitch, low-frequency sounds the elephants make,
0:14:32 > 0:14:33it gets called infra-sound.
0:14:33 > 0:14:36- Yep.- Are there particular situations in which they use that?
0:14:36 > 0:14:39Does it work better in some environments than others?
0:14:39 > 0:14:40Yeah, I mean, generally speaking,
0:14:40 > 0:14:42the infra-sound an elephant will use
0:14:42 > 0:14:45because they can communicate over such vast distances.
0:14:45 > 0:14:48So, when a herd of elephants is travelling, they spread out,
0:14:48 > 0:14:51which could be over, say, 50-250 metres apart.
0:14:51 > 0:14:55- Right.- And if you can imagine one's all the way over there and one's here.
0:14:55 > 0:14:57And one wants to say, we're going this way, just for an example,
0:14:57 > 0:14:59they will communicate through low frequency.
0:14:59 > 0:15:02And so, is there evidence that they're picking up all of this sound
0:15:02 > 0:15:06just with their ears or is there any other way that they're detecting that infra-sound?
0:15:06 > 0:15:08Yes, so technically there's two ways, really,
0:15:08 > 0:15:09that elephants tend to favour.
0:15:09 > 0:15:11I mean, obviously, they have got very big ears.
0:15:11 > 0:15:13The other way they pick up is through their feet.
0:15:13 > 0:15:16They've got a big, squidgy cushion behind their toenails,
0:15:16 > 0:15:19so when they walk it sort of sucks up and when they put their foot on
0:15:19 > 0:15:20the floor, it increases the surface area.
0:15:20 > 0:15:23Now, if they're walking over vast distances, they can actually pick up
0:15:23 > 0:15:26these vibrations, so by putting their foot flat on the floor,
0:15:26 > 0:15:30they feel the vibrations, whatever the communication may be, through infra-sound.
0:15:30 > 0:15:32APPLAUSE
0:15:36 > 0:15:38So, the elephants are really hearing the sound in two ways.
0:15:38 > 0:15:40They're experiencing it in two ways.
0:15:40 > 0:15:44They hear it as a sound and they're also picking it up by feeling it in
0:15:44 > 0:15:48their feet. And the real advantage of that is the low-frequency sounds
0:15:48 > 0:15:51pass very, very well through solid things like the ground.
0:15:51 > 0:15:54And that means that actually the low-frequency sounds that they're
0:15:54 > 0:15:57making with the infra-sound can travel a long way and be detected
0:15:57 > 0:16:00through another elephant's feet quite some distance away,
0:16:00 > 0:16:02in a way that a low-frequency sound might struggle to be carried
0:16:02 > 0:16:04by the air.
0:16:04 > 0:16:06This, just one advantage of sound.
0:16:06 > 0:16:11And, in fact, sound is an incredibly powerful way, efficient way,
0:16:11 > 0:16:14of sharing communication information.
0:16:14 > 0:16:16It's very fast-moving.
0:16:16 > 0:16:19The speed of sound is around 300 metres per second,
0:16:19 > 0:16:22so you can get a signal out there very quickly.
0:16:22 > 0:16:25It works in the dark. It works if something's behind you.
0:16:25 > 0:16:27It works if your eyes are closed.
0:16:27 > 0:16:30When you hear a sound, it means an event has happened.
0:16:30 > 0:16:31It can suddenly start.
0:16:31 > 0:16:35This is one of the reasons why, throughout nature,
0:16:35 > 0:16:39when an animal wants to send an alarm signal, if it can do,
0:16:39 > 0:16:40it will do so with sound.
0:16:42 > 0:16:45But actually, we don't only use sound for very, very basic things
0:16:45 > 0:16:47like alarm calls.
0:16:47 > 0:16:50Because once you've got a sound, you can vary how loud it is.
0:16:50 > 0:16:52You can vary what its pitch is.
0:16:52 > 0:16:53You can vary its rhythm.
0:16:53 > 0:16:55And you can have interactions with sounds.
0:16:55 > 0:16:58You can have conversations with sounds.
0:16:58 > 0:17:02And I've got quite a surprising example of one of those conversations now.
0:17:02 > 0:17:04Going to play you a sound, see if you can recognise it.
0:17:04 > 0:17:08HIGH-PITCHED BUZZING
0:17:10 > 0:17:13Anyone know what that is? Yep.
0:17:13 > 0:17:14A vacuum cleaner.
0:17:14 > 0:17:16It's not a vacuum cleaner.
0:17:16 > 0:17:20We're not quite having conversations with those yet. Any other guesses?
0:17:20 > 0:17:22- Yes. Yep.- Mosquito.
0:17:22 > 0:17:23It's a mosquito.
0:17:23 > 0:17:26Yes. One of the horrible things that you hear flying around if you're
0:17:26 > 0:17:29somewhere warm enough to support mosquitoes.
0:17:29 > 0:17:34Unlike vacuum cleaners, mosquitoes make this sound and...
0:17:34 > 0:17:37We don't quite know... I always assumed they were kind of saying,
0:17:37 > 0:17:39"I'm in your hotel room and I'm going to bite you."
0:17:39 > 0:17:43But it turns out they're sending a rather more complex signal than that.
0:17:43 > 0:17:46And to tell us more about this, I'd like to introduce,
0:17:46 > 0:17:47from the University of Greenwich,
0:17:47 > 0:17:50Professor Gay Gibson and Lionel Feugere.
0:17:56 > 0:17:59How are mosquitoes making that sound?
0:17:59 > 0:18:02That sound is just purely the sound that's made when they beat their
0:18:02 > 0:18:04- wings to fly.- OK. So when they're flying, it's the sound they make?
0:18:04 > 0:18:08- Exactly. Yep.- And is that the whole story, is that the only thing that's going on?
0:18:08 > 0:18:10It's not the whole story, no.
0:18:10 > 0:18:14We've known for a long time that male mosquitoes can hear the sound
0:18:14 > 0:18:16of a female flying by.
0:18:16 > 0:18:19So we know it's got something to do with mating, but we didn't know the
0:18:19 > 0:18:22whole story until we investigated it a little bit further.
0:18:22 > 0:18:24OK. And is that the set-up that we've got here?
0:18:24 > 0:18:28- Yeah, that's what we've got here. - Would you like to take us through it?- Yes, sure.
0:18:28 > 0:18:30So, we all know that sound,
0:18:30 > 0:18:33that irritating sound that mosquitoes make.
0:18:33 > 0:18:40And we can study it more in depth by recording the sound that they make.
0:18:40 > 0:18:44And so we've done that here, we've brought in the apparatus that we used.
0:18:44 > 0:18:48- AMPLIFIED BUZZING - That's a mosquito that's flying.
0:18:48 > 0:18:50So what we can see here,
0:18:50 > 0:18:52they are two mosquitoes and they are held just with a little bit of
0:18:52 > 0:18:54beeswax on the end of a...
0:18:54 > 0:18:56Of a very fine, fine wire.
0:18:56 > 0:19:00- OK.- And then on top of that, this yellow box there,
0:19:00 > 0:19:02that's an old-fashioned
0:19:02 > 0:19:06phonograph needle that we used to listen to records with.
0:19:06 > 0:19:07And they're still very useful,
0:19:07 > 0:19:11they pick up very fine vibrations from that wire,
0:19:11 > 0:19:14to listen in on the mosquitoes' wing beats.
0:19:14 > 0:19:17OK, so at the moment, they're not flying because...
0:19:17 > 0:19:20That's right. So when they've got a piece of paper under their feet there,
0:19:20 > 0:19:23they think they're on the ground, so they fold their wings back.
0:19:23 > 0:19:26But if someone could help us demonstrate this...
0:19:26 > 0:19:27Yeah, we need a volunteer.
0:19:27 > 0:19:30Can I have...? Can I have you there with the checked shirt?
0:19:30 > 0:19:33And the dark jacket. Thank you very much.
0:19:37 > 0:19:39- What's your name?- Sachin.
0:19:39 > 0:19:42Sachin. Now, Sachin, I need to emphasise to you,
0:19:42 > 0:19:45the importance of being super gentle with the mosquitoes.
0:19:45 > 0:19:49- OK?- We don't want to hurt them. - No. Thank you very much, Sachin.
0:19:49 > 0:19:51Now, Gay's going to tell you exactly what to do.
0:19:51 > 0:19:52OK, if you come around here.
0:19:52 > 0:19:55- Do you want to step forward?- I think you can see this little piece of
0:19:55 > 0:19:57white paper here. So, in a minute,
0:19:57 > 0:19:59I'm going to ask you to take the paper away
0:19:59 > 0:20:02and then we're going to listen the sound that we hear.
0:20:02 > 0:20:06So, this one is a female mosquito sound.
0:20:06 > 0:20:09Could you please gently take that piece of paper away?
0:20:09 > 0:20:11MEDIUM-PITCHED BUZZING
0:20:11 > 0:20:13Oops.
0:20:13 > 0:20:16And she's immediately making a sound.
0:20:16 > 0:20:19- LOW-PITCHED BUZZING - That's a female wing-beat frequency.
0:20:19 > 0:20:21OK. Can we hear the male?
0:20:21 > 0:20:24Yeah. Let's do that. I'll put this one back myself.
0:20:26 > 0:20:29Would you like to take the male one away?
0:20:29 > 0:20:30Listen to this one, what's different?
0:20:30 > 0:20:34HIGH-PITCHED BUZZING
0:20:34 > 0:20:38- It does sound very different, doesn't it?- Yeah. Much higher tone.
0:20:38 > 0:20:42- OK.- Males have the high voices and females have the low voices.
0:20:43 > 0:20:46But the more interesting thing is what happens when they can both hear
0:20:46 > 0:20:48each other.
0:20:48 > 0:20:51So we're going to turn these mosquitoes off now.
0:20:53 > 0:20:55OK. So, now we're going to take them both off.
0:20:56 > 0:20:58Yes.
0:20:58 > 0:21:01OK. Listen what happens when they can hear each other.
0:21:01 > 0:21:03LOW-PITCHED BUZZING That's the female.
0:21:03 > 0:21:07HIGH-PITCHED BUZZING There's the male.
0:21:07 > 0:21:09BUZZING HARMONISES
0:21:10 > 0:21:13It sounds like they're bringing their voices together.
0:21:13 > 0:21:18They are indeed. They're going up and down a little bit.
0:21:18 > 0:21:20Hang on. Is this a duet?
0:21:22 > 0:21:24It is exactly a duet.
0:21:24 > 0:21:29And they can make this interaction between each other to help identify,
0:21:29 > 0:21:32"Are you the right species? Are you the one I want to mate with?"
0:21:32 > 0:21:36So, that's the way they communicate, whether or not it's a good match.
0:21:36 > 0:21:38It's a love song. I can't believe it.
0:21:38 > 0:21:41Sachin, thank you very much. Thank you. Fantastic.
0:21:44 > 0:21:46Beautiful work.
0:21:46 > 0:21:47We can look at this on the screen.
0:21:50 > 0:21:53So, Gay, I think you've got a visual example of this, is that right?
0:21:53 > 0:21:56Yeah, we have a recording we made earlier.
0:21:56 > 0:21:59So, this is a visual representation of that song - that duet -
0:21:59 > 0:22:02that you recorded earlier. Can you talk us through this?
0:22:02 > 0:22:04Yeah, certainly. So, here are the two mosquitoes.
0:22:04 > 0:22:07This is the female going along at a steady frequency.
0:22:07 > 0:22:10And here's the male. You can see he's going up and then down.
0:22:10 > 0:22:13- And then...- Can we hear that? - We can hear how that sounds.
0:22:13 > 0:22:18BUZZING HARMONISES
0:22:18 > 0:22:20- PITCH OF BUZZING LOWERS - Dipping right down.- OK.
0:22:20 > 0:22:23And then they're coming towards the same pitch.
0:22:23 > 0:22:26Yeah, they're having a little dialogue.
0:22:27 > 0:22:29It really is in harmony, isn't it?
0:22:34 > 0:22:37Till finally they settle on the harmony.
0:22:37 > 0:22:40That's extraordinary. I don't know if I'm emotionally ready for really
0:22:40 > 0:22:42romantic mosquitoes.
0:22:42 > 0:22:45What they're doing is producing a song the whole time.
0:22:45 > 0:22:49The whole time they're flying, they're doing this harmonisation.
0:22:49 > 0:22:51Why can't they just look at each other?
0:22:51 > 0:22:53Why do they need to do this?
0:22:53 > 0:22:57Well, they need to use sound because most mosquitoes are very nocturnal,
0:22:57 > 0:22:58so they don't have very good vision,
0:22:58 > 0:23:02but sound will carry much further than vision.
0:23:02 > 0:23:04And they're not just emitting the sound at each other,
0:23:04 > 0:23:08they're actually changing their sound till they sound similar.
0:23:08 > 0:23:09Yes, that's right - yes.
0:23:09 > 0:23:12They need to keep flying to be getting anywhere, but
0:23:12 > 0:23:14then they're also simultaneously,
0:23:14 > 0:23:16independently changing this frequency
0:23:16 > 0:23:20- in order to come to a decision to mate with each other.- Amazing.
0:23:20 > 0:23:23Thank you very, very much, Gay. Thank you very much, Lionel.
0:23:33 > 0:23:35Animals aren't just using sounds to signal alarm,
0:23:35 > 0:23:37they're not just using it for mating calls.
0:23:37 > 0:23:41You can see here they're using sound in a really complex, nuanced way,
0:23:41 > 0:23:43for a real conversation.
0:23:43 > 0:23:45And, for most mosquitoes,
0:23:45 > 0:23:48it's incredibly important that they can manage this.
0:23:48 > 0:23:50It's vital to their mating success.
0:23:51 > 0:23:55So, we've seen stridulation being an excellent way of making sound.
0:23:55 > 0:24:00We've seen beating wings as another way of making sound.
0:24:00 > 0:24:03Another way that you often find sound being produced and controlled
0:24:03 > 0:24:09in the animal world is by using breath, controlling breath.
0:24:09 > 0:24:14Now, I've got some examples here of creatures who are very good at using
0:24:14 > 0:24:15their breath to make a sound.
0:24:15 > 0:24:19These guys are Madagascan hissing cockroaches.
0:24:19 > 0:24:22What they do is they use breath to produce an alarm call.
0:24:22 > 0:24:24And I need a volunteer
0:24:24 > 0:24:30who is simultaneously extremely brave and also going to be very,
0:24:30 > 0:24:32very gentle with a Madagascan hissing cockroach.
0:24:32 > 0:24:34Come and pick one up for me.
0:24:34 > 0:24:36Let me have a look. Let me have a look.
0:24:36 > 0:24:39Can I have you in the red jumper?
0:24:39 > 0:24:41Thank you very much. Are you feeling brave?
0:24:42 > 0:24:43Thank you very much.
0:24:44 > 0:24:47- Now, what's your name?- Orla. - Orla? Lovely to meet you, Orla.
0:24:47 > 0:24:50Would you want to have a go at picking one of these
0:24:50 > 0:24:53up for me? What we're going to do is see what sound they make when you do
0:24:53 > 0:24:56that. OK. So, you and I need to be quiet.
0:24:56 > 0:25:02I'll put the mic in. You reach in and very gently pick one up.
0:25:06 > 0:25:09HISSING
0:25:18 > 0:25:21Amazing. Thank you very much, Orla. Thank you.
0:25:26 > 0:25:30So, I'm going to suggest that we bring out a really qualified wrangler of
0:25:30 > 0:25:32cockroaches to go in in a bit more detail.
0:25:32 > 0:25:34We're going to have a look at these guys
0:25:34 > 0:25:36and actually how they make these sounds. Is that OK? This is Ed.
0:25:40 > 0:25:43HISSING
0:25:43 > 0:25:44OK.
0:25:44 > 0:25:47So, if we look close up...
0:25:49 > 0:25:52So, this is just a cockroach that Ed's holding up to the camera.
0:25:53 > 0:25:54We can see along here...
0:25:56 > 0:25:57..those are spiracles.
0:25:57 > 0:26:01That's how insects get air into their body for respiration,
0:26:01 > 0:26:03how they're getting oxygen in and carbon dioxide out.
0:26:03 > 0:26:06It just diffuses into the holes.
0:26:06 > 0:26:10What these cockroaches can do is they can close all but one of these
0:26:10 > 0:26:15spiracles and then press that abdomen in to force all of the air
0:26:15 > 0:26:19out through just one hole and that's how we get this TSSSSSSS sound.
0:26:21 > 0:26:22OK.
0:26:22 > 0:26:24Coming out from the side here.
0:26:24 > 0:26:25OK.
0:26:26 > 0:26:27Thank you very much, Ed.
0:26:38 > 0:26:42Now we, like cockroaches, move air around to breathe.
0:26:42 > 0:26:43But we do it slightly differently.
0:26:43 > 0:26:46We're not letting air permeate through our spiracles,
0:26:46 > 0:26:49we draw air in and out of our lungs and that's how we breathe.
0:26:49 > 0:26:51And we, like lots of other mammals,
0:26:51 > 0:26:54have turned that into a way of making a sound.
0:26:54 > 0:26:57Now we don't make a noisy, hissing sound,
0:26:57 > 0:27:01we produce a rather more regular vibration sound,
0:27:01 > 0:27:03a bit more like the cricket's wings.
0:27:03 > 0:27:05Now, how do we make this vibration?
0:27:05 > 0:27:08Can you all just put your hands on your throats for me?
0:27:08 > 0:27:12And now go, TSSSSSSS, like the hissing cockroach.
0:27:12 > 0:27:14HISSING
0:27:14 > 0:27:15I can't feel anything happening here.
0:27:15 > 0:27:19Now try that again but go... ZZZZZZ, like you're saying zoo.
0:27:19 > 0:27:22BUZZING
0:27:22 > 0:27:24What can you feel?
0:27:24 > 0:27:27- A vibration.- Exactly. You feel a vibration in your throat.
0:27:27 > 0:27:30Now, that's actually the source of the sounds that we're using.
0:27:30 > 0:27:33It's in what's called the voice box, also called the larynx.
0:27:33 > 0:27:36Inside that, there are two pieces of tissue called the vocal folds and we
0:27:36 > 0:27:38vibrate those to make that sound.
0:27:38 > 0:27:41Now, let's see that larynx in action.
0:27:41 > 0:27:44I'd now like to welcome Professor Martin Birchall
0:27:44 > 0:27:48and willing soprano singer Francesca Chiejina. Fantastic!
0:27:58 > 0:28:02Can I ask you to sit down?
0:28:02 > 0:28:04And all of this is being operated by Idris.
0:28:04 > 0:28:08Martin, you're our consultant head-and-neck surgeon at UCLH.
0:28:08 > 0:28:12- Yep.- And you, Francesca, are a soprano singer from the
0:28:12 > 0:28:14Royal Opera House Jet Parker Young Artists' Programme.
0:28:14 > 0:28:18What we're going to do is use this rather alarmingly large
0:28:18 > 0:28:21piece of equipment to have a look at a larynx in action, I understand.
0:28:21 > 0:28:23- We are.- So, what actually is this?
0:28:23 > 0:28:27So, this is equipment that we use in the clinic and the hospitals every
0:28:27 > 0:28:31day. It's a nasal endoscope and we use it for looking at the
0:28:31 > 0:28:32throat and diagnosing people.
0:28:32 > 0:28:34OK. Can we actually do that now?
0:28:34 > 0:28:36- Absolutely, we can.- OK.
0:28:36 > 0:28:37- Are you ready for this?- Yes.
0:28:37 > 0:28:39Now, what's the actual device like?
0:28:39 > 0:28:42Yeah. So, what we've got here, there's three bits to this.
0:28:42 > 0:28:45We've got a light source here, we've got a processor,
0:28:45 > 0:28:48and we've got a strobe light generator.
0:28:48 > 0:28:49This itself is the endoscope.
0:28:49 > 0:28:52In the old days, these used to have...
0:28:52 > 0:28:54They were fibre optics.
0:28:54 > 0:28:57And so you'd get an image that was made up like the eye of an insect.
0:28:57 > 0:29:01Nowadays, we're fortunate enough to have very high-definition cameras,
0:29:01 > 0:29:04much better than the ones in your phones, right on the ends,
0:29:04 > 0:29:06- so we can see right inside.- OK.
0:29:06 > 0:29:08- Can we do that now? Is that all right with you?- Yes.
0:29:08 > 0:29:11So, we're going to drop the endoscope down actually
0:29:11 > 0:29:13to look right at Francesca's larynx.
0:29:13 > 0:29:15That's precisely what we're going to do.
0:29:15 > 0:29:18You'll be able to see the image on the screen there.
0:29:18 > 0:29:20OK. Thank you very much. So, breathe gently through your nose,
0:29:20 > 0:29:22relax your shoulders.
0:29:22 > 0:29:24This is going to tickle a little bit.
0:29:24 > 0:29:25Could I see the screen, Idris?
0:29:25 > 0:29:28Thank you very much.
0:29:28 > 0:29:31- So, is that the back of the nose? - No, we're actually going through the nose.
0:29:31 > 0:29:33The nose is very important for the voice, actually.
0:29:33 > 0:29:36It's an air-conditioning device.
0:29:36 > 0:29:38So, it warms, humidifies,
0:29:38 > 0:29:39filters the air that we breathe
0:29:39 > 0:29:43to make sure everything we breathe in is nice and clean. That's why
0:29:43 > 0:29:46it's bad to breathe through your mouth.
0:29:46 > 0:29:48And that's the larynx.
0:29:48 > 0:29:52It is. What we're looking at there, it's a very alien-looking thing,
0:29:52 > 0:29:55isn't it, is the larynx, in the middle of the view there.
0:29:55 > 0:29:58The vocal cords are the two grey things moving in and out,
0:29:58 > 0:30:00forming a V-shape in the centre.
0:30:00 > 0:30:03The big, floppy thing is called the epiglottis, it's like a trap door.
0:30:03 > 0:30:06It stops food and drink going down the wrong way.
0:30:06 > 0:30:10And the two round things towards the back are called arytenoids -
0:30:10 > 0:30:13they're bones that move the vocal cords in and out.
0:30:13 > 0:30:16Francesca, would you feel OK just to sing a note for us?
0:30:16 > 0:30:17OK.
0:30:19 > 0:30:22- Any note?- Absolutely.- Go for it.
0:30:22 > 0:30:27SHE SINGS MEDIUM-PITCHED NOTE
0:30:33 > 0:30:36So, I could hear and see the larynx came together.
0:30:36 > 0:30:37I couldn't see it moving.
0:30:37 > 0:30:40You'll see it now. We'll now switch to a different light source that's
0:30:40 > 0:30:45going to flash light out of phase with the fundamental frequency of
0:30:45 > 0:30:47the sound she makes. Basically, it's strobing,
0:30:47 > 0:30:51like in discos when I was a young man, a long time ago.
0:30:51 > 0:30:53It slows down movement.
0:30:53 > 0:30:54You should see this here.
0:30:54 > 0:30:58So, if you'd like to make a slightly higher-frequency sound, Francesca.
0:30:58 > 0:31:03SHE SINGS HIGH-PITCHED NOTE
0:31:08 > 0:31:10- Very good.- Fantastic.- I could feel it.
0:31:10 > 0:31:12- Well done!- Now, could you do a glissando for us?
0:31:12 > 0:31:15From as low as you can, to as high as you can.
0:31:15 > 0:31:20OK. It feels so weird. OK.
0:31:22 > 0:31:28SHE SINGS GLISSANDO
0:31:28 > 0:31:32SHE SINGS GLISSANDO
0:31:32 > 0:31:37Beautiful. So, you can see the vocal cords lengthening and shortening.
0:31:51 > 0:31:55How was Francesca able to move her vocal folds so very quickly?
0:31:55 > 0:31:58She's moving them around 2,000 times a second,
0:31:58 > 0:32:00much too fast for us to be able to see.
0:32:00 > 0:32:02Now, how fast can you move your body?
0:32:03 > 0:32:08Clap your hands for me. I want to see how quickly you can clap your hands together.
0:32:08 > 0:32:11That's good. We've got some good clapping there.
0:32:11 > 0:32:13Some top clapping there.
0:32:15 > 0:32:17Yeah. OK. Now, I can't lie.
0:32:17 > 0:32:19I could still see all your hands moving.
0:32:19 > 0:32:21You weren't going as quickly as the vocal cords.
0:32:21 > 0:32:22Let's try it with your feet.
0:32:22 > 0:32:24How quickly can you tap your feet on the ground?
0:32:24 > 0:32:26Very good. That's very good.
0:32:26 > 0:32:28Very quick.
0:32:28 > 0:32:30I can still see your knees moving.
0:32:30 > 0:32:32You're not quite going that fast.
0:32:32 > 0:32:34So, let's try something else.
0:32:34 > 0:32:36Blow a raspberry at me, please.
0:32:42 > 0:32:44OK. Enough raspberries.
0:32:44 > 0:32:45Thank you. Thank you.
0:32:45 > 0:32:47Now, that was fast.
0:32:47 > 0:32:50And that's because, when you blow a raspberry,
0:32:50 > 0:32:53you do something very similar to how you make a sound at your larynx.
0:32:53 > 0:32:57Instead of moving your hands back and forth to clap or your feet up and down to tap,
0:32:57 > 0:33:00you don't move your lips up and down to blow a raspberry.
0:33:00 > 0:33:03You blow air through them.
0:33:03 > 0:33:06And that's exactly what happens when you are making a sound at your
0:33:06 > 0:33:07larynx. You blow air through.
0:33:07 > 0:33:09So, you're not moving the larynx back and forth.
0:33:09 > 0:33:12You're using your breath to control that.
0:33:12 > 0:33:14And, for this next demonstration,
0:33:14 > 0:33:18of exactly how that makes us make a sound in our larynx,
0:33:18 > 0:33:21I need two big balloons.
0:33:24 > 0:33:25And a volunteer.
0:33:26 > 0:33:28OK. Can I have you, please?
0:33:28 > 0:33:32Thank you very much. Fantastic!
0:33:32 > 0:33:34Thank you. Just ducking underneath this.
0:33:36 > 0:33:38Can you come and stand here for me, please?
0:33:40 > 0:33:41OK.
0:33:42 > 0:33:46Thank you. Now, this is extremely normal, as I'm sure you'll agree.
0:33:46 > 0:33:48- What's your name?- Isaac.
0:33:48 > 0:33:52Isaac. Now, what I'm going to ask you to do, Isaac, in just a second,
0:33:52 > 0:33:56is to take a leaf blower and we're going to blow some air between these
0:33:56 > 0:33:59two big balloons. People in the audience, I want you to think,
0:33:59 > 0:34:02when we blow a big blast of air through these balloons,
0:34:02 > 0:34:05is that going to push the balloons further apart or is it going to pull
0:34:05 > 0:34:10the balloons together? Put your hands up if you think it's going to blow them apart?
0:34:10 > 0:34:14Excellent. Put your hands up if you think it's going to pull them together. Very good.
0:34:14 > 0:34:15Very good. Slightly more for apart.
0:34:15 > 0:34:17In that case, what we're going to do is to test this.
0:34:17 > 0:34:19So, what I need you to do, Isaac,
0:34:19 > 0:34:24is to pop on some safety glasses and pop these on.
0:34:24 > 0:34:27OK. And now, for your lifelong ambition...
0:34:30 > 0:34:32..an enormous leaf blower. I'm going to come this side.
0:34:32 > 0:34:34Now, I'm going to count you in.
0:34:34 > 0:34:37You turn it on there and kind of point it right through the middle.
0:34:37 > 0:34:41OK. Three, two, one...go.
0:34:41 > 0:34:45BLOWER WHIRS
0:34:45 > 0:34:48They're moving. They're moving together, aren't they?
0:34:48 > 0:34:50Keep going, keep going. And...
0:34:54 > 0:34:58OK. Fantastic! Turn off the blower, Isaac. Thank you.
0:35:00 > 0:35:03Now, don't go anywhere.
0:35:03 > 0:35:06So, if you thought they were going to get pulled together, you were right.
0:35:06 > 0:35:08It's very counterintuitive.
0:35:08 > 0:35:11But what happens when you blast the air through the middle of these two
0:35:11 > 0:35:14balloons is something called the Bernoulli principle.
0:35:14 > 0:35:18The Bernoulli principle says, when you have air that's moving more quickly,
0:35:18 > 0:35:23the air pressure within that air is lower than in the surrounding areas.
0:35:23 > 0:35:27What that does is it pulls the balloons together.
0:35:27 > 0:35:28Not pushing them further apart.
0:35:28 > 0:35:32They're pulled in. This is just like your shower curtain sticking to your
0:35:32 > 0:35:35leg when you're in the shower because the air has been moved round
0:35:35 > 0:35:37by the movement of the water.
0:35:37 > 0:35:39The other thing you'll notice, as we carried on -
0:35:39 > 0:35:41as Isaac carried on blowing -
0:35:41 > 0:35:46was that the balloons also then moved apart and then came back together,
0:35:46 > 0:35:47and they started to bounce.
0:35:47 > 0:35:51They're being pulled apart by things like gravity
0:35:51 > 0:35:54and the Bernoulli forces pulling back in again.
0:35:54 > 0:35:57That's exactly what happens in your larynx.
0:35:57 > 0:36:01You hold the larynx vocal folds together in the larynx.
0:36:01 > 0:36:02You blow air through them,
0:36:02 > 0:36:06and they're pushed apart and snap back together under these forces of
0:36:06 > 0:36:09elasticity and the Bernoulli principle.
0:36:09 > 0:36:11That's giving us those fast vibrations.
0:36:11 > 0:36:12Isaac, thank you.
0:36:16 > 0:36:17Thank you.
0:36:19 > 0:36:20But, is this...
0:36:22 > 0:36:23..the full story of how we make sounds?
0:36:23 > 0:36:27We're making a noise at the larynx by blowing air through the vocal folds
0:36:27 > 0:36:28and causing them to vibrate.
0:36:29 > 0:36:31The vocal folds are amazing.
0:36:31 > 0:36:34They are an incredible piece of anatomy.
0:36:34 > 0:36:37They produce phenomenal ranges of sounds.
0:36:37 > 0:36:41And they're kind of rich with all sorts of different kinds of potential information.
0:36:41 > 0:36:45It's very, very important in terms of how we communicate with sound,
0:36:45 > 0:36:47but it's not the whole story.
0:36:48 > 0:36:51If we record the sound from the vocal folds and play it back,
0:36:51 > 0:36:54it sounds like this.
0:36:54 > 0:36:58MUFFLED SCRATCHING
0:37:00 > 0:37:02Anybody recognise that?
0:37:05 > 0:37:08- It's Jack and Jill.- So, it's a very over-familiar nursery rhyme
0:37:08 > 0:37:11which you can recognise because the sound at the vocal folds -
0:37:11 > 0:37:13it's got the right rhythm, it's got the right pitch.
0:37:13 > 0:37:15That's where you put that information in.
0:37:15 > 0:37:19But it didn't sound like a voice, it didn't sound like somebody talking.
0:37:19 > 0:37:23So, where does this other kind of information come in?
0:37:23 > 0:37:26Well, it turns out it's not enough to make vibrations.
0:37:26 > 0:37:32What you need to do is enhance, amplify, enrich those vibrations.
0:37:32 > 0:37:36And that comes down to another property of how sounds work.
0:37:36 > 0:37:38That's to do with resonance.
0:37:38 > 0:37:40If we can exploit resonance,
0:37:40 > 0:37:45we can make our communication with sound work much more efficiently.
0:37:45 > 0:37:46So, what's resonance?
0:37:46 > 0:37:51Resonance is just a characteristic of objects, things in the world,
0:37:51 > 0:37:54from molecules up to mountains - things, objects,
0:37:54 > 0:37:57have a frequency at which they will maximally vibrate.
0:37:57 > 0:38:01And we can use this property when we're making communication sounds to
0:38:01 > 0:38:05help maximise the sound vibrations that we're producing and therefore
0:38:05 > 0:38:08enhance their communicative properties.
0:38:08 > 0:38:12I'm going to show you how this works with an extremely simple demo.
0:38:15 > 0:38:19So, you can think of everything as having a rate at which it moves
0:38:19 > 0:38:22most efficiently, at which it will vibrate maximally.
0:38:22 > 0:38:25And here, we're seeing how that can be affected by the shapes of objects.
0:38:25 > 0:38:27Here, we've just got, as our objects,
0:38:27 > 0:38:30we've got four lovely Christmas baubles and,
0:38:30 > 0:38:32for the purpose of this demonstration,
0:38:32 > 0:38:35I want you to think of the whole thing - the bauble and the string -
0:38:35 > 0:38:37as being the shape of the object.
0:38:37 > 0:38:41What I'm going to do is move this ball here.
0:38:41 > 0:38:45What I want you to do is watch what happens to these guys.
0:38:52 > 0:38:56Now, you should notice that one of these Christmas baubles
0:38:56 > 0:39:00starts to move at a more exaggerated rate than the other ones.
0:39:00 > 0:39:03Can anyone call out the colour - the one that's moving the most?
0:39:03 > 0:39:04- ALL:- Red.- It's red, exactly.
0:39:04 > 0:39:07Now, what does red have in common with this one?
0:39:07 > 0:39:09It's the same length. So, the shape...
0:39:09 > 0:39:12The overall shape of the whole thing is most similar across those two.
0:39:12 > 0:39:14And it's meaning, when I move this one,
0:39:14 > 0:39:17it's putting in the right kind of movement to vibrate something of a
0:39:17 > 0:39:20similar shape. So, if I change the shape of this guy...
0:39:22 > 0:39:24..by shortening the string...
0:39:28 > 0:39:30..and then do exactly the same thing.
0:39:30 > 0:39:32I'm just going to set this one moving.
0:39:36 > 0:39:39So now you can see, with this different shape,
0:39:39 > 0:39:41a different Christmas bauble is moving maximally...
0:39:42 > 0:39:44..and what's happening here
0:39:44 > 0:39:47is I'm putting the kind of force in at the right
0:39:47 > 0:39:49kind of speed to cause
0:39:49 > 0:39:53maximal vibration with this Christmas bauble.
0:39:53 > 0:39:55And of course we do this all the time.
0:39:55 > 0:39:59We have a very intuitive understanding of how we can put
0:39:59 > 0:40:03the right kind of force into things that we want to move.
0:40:03 > 0:40:05If you ride on a swing, you know how to push that
0:40:05 > 0:40:08at the right kind of speed and the right kind of
0:40:08 > 0:40:10force to make yourself swing.
0:40:10 > 0:40:12And you do the same thing when you use your voice.
0:40:12 > 0:40:14When you make a sound with your voice,
0:40:14 > 0:40:18you're actually exploiting that kind of pressure of your air to get the
0:40:18 > 0:40:22right kind of resonance properties for the vibrations that you make.
0:40:22 > 0:40:24Sounds are made by vibrations
0:40:24 > 0:40:28and those vibrations are made bigger when the objects we make vibrate
0:40:28 > 0:40:30can hit their resonance frequency.
0:40:30 > 0:40:33This, amongst other things, can mean the sounds can be louder.
0:40:34 > 0:40:37Now we can see a more dramatic demonstration of this if we take a
0:40:37 > 0:40:41more complex object and explore its resonance characteristics.
0:40:41 > 0:40:46What we're going to try and do is find and exploit the resonance frequency of a wineglass.
0:40:48 > 0:40:51Now, when you make a wineglass make a sound like this,
0:40:51 > 0:40:55what you're doing is you're finding the resonance frequency.
0:40:55 > 0:40:57HUMMING
0:41:02 > 0:41:05So, I'm putting in the right kind of force at the right kind of speed to
0:41:05 > 0:41:08start resonating this glass and we can hear that.
0:41:08 > 0:41:13However, if we record that sound and play that sound back into the glass,
0:41:13 > 0:41:17we can see much more dramatic effects of that vibration.
0:41:17 > 0:41:22At this stage, I just need to ask everybody to put their earplugs in.
0:41:22 > 0:41:26You guys put your ear plugs in, and your safety glasses.
0:41:28 > 0:41:32So, what Fran has done earlier is she's calculated the resonance frequency
0:41:32 > 0:41:36of this wineglass and she's going to generate the right sound and
0:41:36 > 0:41:40put it through under great levels of intensity out of this loud speaker.
0:41:40 > 0:41:43And we'll start to see what that does to the wineglass.
0:41:43 > 0:41:47And we can see this because we've got the high-speed camera again.
0:41:47 > 0:41:50So, we need more light for that and you'll see that appearing on the
0:41:50 > 0:41:53screen. OK. Has everybody got their ears covered up?
0:41:54 > 0:41:55Off we go.
0:41:55 > 0:41:59HUMMING
0:42:01 > 0:42:03HUMMING AMPLIFIES
0:42:05 > 0:42:06There we go.
0:42:10 > 0:42:11That's amazing.
0:42:15 > 0:42:17If I leap over the debris,
0:42:17 > 0:42:22can you see how much that wineglass is moving before it breaks?
0:42:22 > 0:42:26How much those vibrations are causing it to distort and shake.
0:42:28 > 0:42:30Just when you think it can't
0:42:30 > 0:42:32possibly tolerate that much movement,
0:42:32 > 0:42:34it stops tolerating that much movement
0:42:34 > 0:42:37and we see the whole thing break to pieces.
0:42:40 > 0:42:41Whoa!
0:42:44 > 0:42:46That's the power of resonance.
0:42:48 > 0:42:51If you want to send your message further,
0:42:51 > 0:42:54resonance can really help you.
0:42:54 > 0:42:57But how are we exploiting resonance in our own bodies?
0:42:57 > 0:42:59I mean, to be brutally honest,
0:42:59 > 0:43:02we're not exploding wineglasses or anything dramatic like that.
0:43:02 > 0:43:07Actually, we're doing something a bit more like a musical instrument.
0:43:07 > 0:43:09I've got an example of a musical instrument here.
0:43:09 > 0:43:10Thank you very much, Natasha.
0:43:10 > 0:43:12So, we've got the basics of a musical instrument.
0:43:12 > 0:43:15We've got a string. I'm going to make that string vibrate
0:43:15 > 0:43:16by plucking it.
0:43:16 > 0:43:19DULL THUMP
0:43:19 > 0:43:21Now you can kind of hear something, can't you?
0:43:21 > 0:43:23You can see something's moving.
0:43:23 > 0:43:24There's not very much sound there.
0:43:27 > 0:43:31What we can do is make that much more impressive
0:43:31 > 0:43:33by bringing in a bit more resonance.
0:43:37 > 0:43:38Thank you.
0:43:38 > 0:43:41So, this is just a tea chest.
0:43:41 > 0:43:42It's an empty tea chest.
0:43:42 > 0:43:44Well, it's not empty. It's filled with air.
0:43:44 > 0:43:47What we're going to do is use the resonance properties
0:43:47 > 0:43:51of the tea chest and the air inside it to really exploit the vibrations
0:43:51 > 0:43:53that we're making with the exact same string,
0:43:53 > 0:43:57and the exact same stick that you just saw before.
0:43:57 > 0:43:59If we do that, you can hear a sound.
0:43:59 > 0:44:02LOW-PITCHED NOTE A much louder sound.
0:44:02 > 0:44:05LOW-PITCHED NOTE
0:44:05 > 0:44:09Where's that sound actually coming from? Are we hearing the sound of string?
0:44:09 > 0:44:10We're probably not.
0:44:10 > 0:44:13We can actually image that with this fantastic device here.
0:44:13 > 0:44:16This is actually an acoustic camera.
0:44:16 > 0:44:19It's really a rather beautiful array of microphones.
0:44:19 > 0:44:22It looks like a spectacular tree.
0:44:22 > 0:44:27What that's going to be used for is to give a spatial location to where
0:44:27 > 0:44:29sounds are coming from.
0:44:29 > 0:44:31So, if I make a sound...
0:44:31 > 0:44:33Tch!
0:44:33 > 0:44:34Tch!
0:44:34 > 0:44:36Tch!
0:44:36 > 0:44:37Tch!
0:44:37 > 0:44:41You can see that the sound source is coming from the front of my face,
0:44:41 > 0:44:43which is correct. That's how I was making that sound.
0:44:43 > 0:44:46Now if we try this with our bass
0:44:46 > 0:44:49and see if we can see that making a sound.
0:44:49 > 0:44:51LOW-PITCHED NOTE
0:44:51 > 0:44:54It's the air, the vibrating air, that's causing the sound.
0:44:54 > 0:44:57It's coming out from the bottom of the bass.
0:44:57 > 0:45:00STRUMMING
0:45:11 > 0:45:13There we go. Thank you very much, acoustic camera.
0:45:18 > 0:45:22So, a simple demonstration of how adding in the resonance here
0:45:22 > 0:45:26of some air inside the box helps us hear the vibration of that string
0:45:26 > 0:45:29completely differently. And we're doing something very similar.
0:45:29 > 0:45:32We're taking the resonance characteristics
0:45:32 > 0:45:33of our own vocal tract,
0:45:33 > 0:45:36and we're using that to shape and enrich
0:45:36 > 0:45:38the sound we make at our larynx.
0:45:38 > 0:45:41So, if we look here at my cutaway head.
0:45:41 > 0:45:45This is just showing you the shape of the air tubes we're sending sound
0:45:45 > 0:45:48into when we make a sound at our larynx.
0:45:48 > 0:45:50The larynx is sitting down here.
0:45:51 > 0:45:53It's sitting down actually in the windpipe -
0:45:53 > 0:45:54it's quite low down in humans,
0:45:54 > 0:45:57much lower down than it is in other primates.
0:45:57 > 0:46:02What that gives us is a much longer tube for making the sounds that we
0:46:02 > 0:46:05make with our voices. It's a long way from our larynx to our lips.
0:46:05 > 0:46:08That's called our vocal tract. It's actually made of two tubes.
0:46:08 > 0:46:10We've got one tube coming up through our mouth,
0:46:10 > 0:46:12one coming up through our nose.
0:46:12 > 0:46:14There are two aspects to this.
0:46:14 > 0:46:18Our lowered larynx gives us a longer tube to make the sounds with.
0:46:18 > 0:46:21It's giving us a richer sound.
0:46:21 > 0:46:22And also, what we can do
0:46:22 > 0:46:26is we can modify the shape of our mouths
0:46:26 > 0:46:28and change the resonance characteristics.
0:46:28 > 0:46:31So, if you all go... Eee!
0:46:31 > 0:46:34- ALL:- Eee!
0:46:34 > 0:46:36- Ooh!- Ooh!
0:46:36 > 0:46:39Now, that's you changing the resonance characteristics of your
0:46:39 > 0:46:42own vocal tract and it's giving you a different sound.
0:46:42 > 0:46:45So, we have a richer sound, we have a more complex sound.
0:46:45 > 0:46:47It's as if we have a musical instrument where we could change
0:46:47 > 0:46:49the shape of it all the time.
0:46:49 > 0:46:52And we use that really importantly for how we communicate
0:46:52 > 0:46:55with sound. Our lowered larynxes are giving us
0:46:55 > 0:46:57this richer range of sound.
0:46:57 > 0:47:02In adult men, we see another movement down of the larynx.
0:47:02 > 0:47:05In adolescents, boys' voices break.
0:47:05 > 0:47:08What that literally means is the larynx moves physically further down.
0:47:08 > 0:47:11And you can see an Adam's apple in the neck of most men.
0:47:11 > 0:47:14This gives men an even longer tube
0:47:14 > 0:47:18to make the sounds of speech in their voice with and it gives them
0:47:18 > 0:47:20a deeper, richer-sounding voice.
0:47:20 > 0:47:25But, it turns out, humans are not the only animals that have a larynx
0:47:25 > 0:47:27which we can manoeuvre in this way.
0:47:29 > 0:47:33Fallow deer - male fallow deer - compete to mate with females.
0:47:33 > 0:47:36Professor David Reby from the University of Sussex
0:47:36 > 0:47:39went to look at how the bucks use their voices to communicate their
0:47:39 > 0:47:43size and try and impress those females and each other.
0:47:46 > 0:47:48Hello, Sophie. Hi, everyone.
0:47:48 > 0:47:50So, today, we're in Petworth Park.
0:47:50 > 0:47:54This time of the year, the fallow deer engage in what we call the rut.
0:47:54 > 0:47:59During the rut, the males produce a very large number of vocalisations,
0:47:59 > 0:48:01- called groans. - DEER GROANS
0:48:01 > 0:48:04And these groans are very low pitch.
0:48:04 > 0:48:07And we believe that they produce this vocalisation in order
0:48:07 > 0:48:10to communicate information about the body size.
0:48:19 > 0:48:22We're going to play back groans which have been resynthesized,
0:48:22 > 0:48:24where I've either lowered the resonances,
0:48:24 > 0:48:28so that the buck sounds a lot larger than it actually is,
0:48:28 > 0:48:31or where I've raised the resonances, to make it sound a lot smaller.
0:48:33 > 0:48:37So, what I'm going to do now is to play the small version.
0:48:37 > 0:48:41LOW-PITCHED GROANS
0:48:42 > 0:48:45Clearly puzzled by the playback.
0:48:47 > 0:48:51I'm going to play back a very large buck. Look at this guy.
0:48:51 > 0:48:53DEEPER-PITCHED GROAN
0:48:53 > 0:48:57We've definitely got their attention here.
0:48:57 > 0:49:00You can see he's clearly intimidated.
0:49:00 > 0:49:03I think you could really see the response of the buck to the first
0:49:03 > 0:49:07sequence, where the caller sounds smaller.
0:49:07 > 0:49:11We had quite a timid reaction from the target animal,
0:49:11 > 0:49:15whereas when we played the groans where the resonance had been lowered
0:49:15 > 0:49:19to make the animal sound a lot larger, we get a much
0:49:19 > 0:49:23stronger response from the target buck.
0:49:29 > 0:49:33David was actually the first scientist to realise that deer
0:49:33 > 0:49:35were able to do this with their voices
0:49:35 > 0:49:38and he's been taking Cat scans of deer vocal tracts.
0:49:38 > 0:49:42You can see that here. So, that's the length of the neck.
0:49:42 > 0:49:47It's giving you some idea of how far they can move their larynx up and down.
0:49:47 > 0:49:50We think we've got fairly impressive vocal tracts.
0:49:50 > 0:49:52Deer are much, much larger
0:49:52 > 0:49:54and they're moving their larynx really a long
0:49:54 > 0:49:57way up and down to create this incredible range of sounds.
0:49:57 > 0:50:02The deeper voice, maybe it suggests power and strength.
0:50:02 > 0:50:04Maybe this has some similar role in humans.
0:50:04 > 0:50:07Maybe this secondary descent of the larynx that boys go through in
0:50:07 > 0:50:11adolescence is adding in aspects of their voice which are potentially
0:50:11 > 0:50:14conveying dominance or size.
0:50:14 > 0:50:18It's certainly possibly giving men the sound of a bigger body without
0:50:18 > 0:50:22actually having to grow a larger and more expensive bigger body.
0:50:22 > 0:50:24We're seeing sounds generally, however,
0:50:24 > 0:50:28as being something we can think of as actions.
0:50:28 > 0:50:31All sounds happen because something happened in the world and the things
0:50:31 > 0:50:35that interacted to cause those sounds to happen also affect the sound.
0:50:35 > 0:50:39As the bodies get bigger, the sounds gets deeper and they get richer.
0:50:41 > 0:50:44We've seen a variety of different ways that animals can communicate
0:50:44 > 0:50:47and they're orchestrating this physics of vibration and resonance
0:50:47 > 0:50:51to help communicate with each other, to send and receive messages.
0:50:51 > 0:50:53And, of course, the more you can vary these sound waves,
0:50:53 > 0:50:57the more complex the messages you can communicate.
0:50:58 > 0:51:04Now, humans are exceptionally good at really rapidly and precisely
0:51:04 > 0:51:07modifying the sound we make when we use our voices.
0:51:07 > 0:51:10We can shape and interrupt the flow of air with our tongues, our lips,
0:51:10 > 0:51:13our teeth, our jaw and, of course,
0:51:13 > 0:51:16this is one of the main ingredients for one of our most important sound
0:51:16 > 0:51:18communications...speech.
0:51:18 > 0:51:20To show exactly how we do this,
0:51:20 > 0:51:23please welcome my friend and colleague, Reeps.
0:51:26 > 0:51:28- Hi.- Thank you.
0:51:34 > 0:51:37Now, Reeps, can you start by taking us through some plosive sounds?
0:51:37 > 0:51:42Plosive sounds are where we make a closure with our lips and then spit
0:51:42 > 0:51:44- the sound out.- Yes, of course.
0:51:44 > 0:51:49HE BEATBOXES
0:52:04 > 0:52:08Now, I've worked in speech for many years and I always used to start all
0:52:08 > 0:52:12my talks by saying human speech is the most complex sound in nature and
0:52:12 > 0:52:15then I met Reeps, and I realised, because you'll have just spotted,
0:52:15 > 0:52:18he was beatboxing. He's one of the world's greatest beatboxers.
0:52:18 > 0:52:21He does this incredible, amazing noise.
0:52:21 > 0:52:24It's the speed at which he's doing things, the sounds he's producing.
0:52:24 > 0:52:26It so much more than we do when we're talking.
0:52:26 > 0:52:29We can actually look at that in a bit more detail.
0:52:29 > 0:52:31- Are you OK to come and stand over here?- Yes. Of course.
0:52:31 > 0:52:35What we've done is we've put Reeps into our MRI machine
0:52:35 > 0:52:38and we've run that like a video camera, so we can actually image
0:52:38 > 0:52:42his vocal tract and how he's changing it while he beatboxes
0:52:42 > 0:52:45and you can see that on the monitor here.
0:52:45 > 0:52:50HE BEATBOXES
0:53:09 > 0:53:11Thank you. Brilliant. Thank you.
0:53:18 > 0:53:19That's absolutely extraordinary.
0:53:19 > 0:53:22You could hear at certain points how he was producing at least two
0:53:22 > 0:53:24different sounds at once.
0:53:24 > 0:53:26And that's not technically supposed to be possible.
0:53:26 > 0:53:27Apparently no-one told you.
0:53:29 > 0:53:32Is it the case that this is just a learnable skill?
0:53:32 > 0:53:34Did you teach yourself this?
0:53:34 > 0:53:37I started because I played lots of instruments when I was younger.
0:53:37 > 0:53:40I wanted to make music all the time and it's a way to internalise music
0:53:40 > 0:53:44very quickly. And I completely taught myself.
0:53:44 > 0:53:46Listening to music, listening to things that are out there,
0:53:46 > 0:53:49it's possible for people to create their own music
0:53:49 > 0:53:53- with themselves all the time.- And could any of us learn to do this?
0:53:53 > 0:53:56Absolutely. Every single person in this room can start exploring sounds.
0:53:56 > 0:53:59We all use 26 sounds in the alphabet.
0:53:59 > 0:54:01Three of those sounds - puh, tuh and kuh -
0:54:01 > 0:54:05can easily become music and you're all welcome to explore.
0:54:05 > 0:54:07- Excellent. Thank you very much, Reeps.- My pleasure.
0:54:07 > 0:54:10If you wouldn't mind just sitting there. Don't go anywhere.
0:54:18 > 0:54:22So, one thing that's really striking is that human vocal abilities,
0:54:22 > 0:54:25if anything, are over-engineered for speech.
0:54:25 > 0:54:28I thought speech was so complex and then I saw things like beatboxing
0:54:28 > 0:54:31and I realise we're actually doing almost the bare minimum
0:54:31 > 0:54:33when we talk to each other.
0:54:33 > 0:54:36So, I wonder if there might be some other aspect of our communication
0:54:36 > 0:54:39and our voices that might have driven our evolution of this
0:54:39 > 0:54:42really extraordinary musical instrument that we have.
0:54:42 > 0:54:46So, please, can I introduce my last guest, Katherine Woodward?
0:54:56 > 0:55:00Now, I've made a movie of you in our scanner,
0:55:00 > 0:55:02looking at your vocal tract.
0:55:02 > 0:55:04- Yes.- Can I position you here?
0:55:04 > 0:55:05Can you sing along to that for us?
0:55:05 > 0:55:07Is that OK? Thank you very much.
0:55:09 > 0:55:13SHE SINGS OPERA
0:55:36 > 0:55:41Lovely. Thank you.
0:55:42 > 0:55:44You can see in Katherine's voice,
0:55:44 > 0:55:46the range and the shape she's creating in her vocal tract
0:55:46 > 0:55:51to produce a sound of such power, such strength, such thrillingness.
0:55:51 > 0:55:55And, of course, we can all potentially learn to do this.
0:55:55 > 0:55:57We might never be as good as Katherine,
0:55:57 > 0:55:59but it's a learnable skill.
0:55:59 > 0:56:00We all learn to speak.
0:56:00 > 0:56:03We can all learn these other kinds of vocal abilities.
0:56:03 > 0:56:07And one theory does suggest that what we might be looking at,
0:56:07 > 0:56:10because we can do so much more than we do when we're normally talking to
0:56:10 > 0:56:14each other, we might have evolved this ability for vocal gymnastics
0:56:14 > 0:56:16before we were ever using it for speaking.
0:56:16 > 0:56:20Possibly, our vocal range and complexity may have been a way for
0:56:20 > 0:56:23our ancestors to win mates, or defend territories,
0:56:23 > 0:56:27much in the same way as we see birds nowadays using sounds to impress
0:56:27 > 0:56:32other birds. Once we'd evolved this absolutely extraordinary musical
0:56:32 > 0:56:36instrument of the human voice, maybe speech was almost an invention,
0:56:36 > 0:56:39an afterthought. It's an afterthought, of course,
0:56:39 > 0:56:42that's created the world we live in, through the gift of language.
0:56:44 > 0:56:48Whether you are a cricket, or cockroach, a deer or an elephant,
0:56:48 > 0:56:51the ability to communicate with sounds can be absolutely critical to
0:56:51 > 0:56:55your survival. Thinking about the human voice as an instrument for
0:56:55 > 0:57:00social, emotional, as well as spoken communication can help us understand possibly
0:57:00 > 0:57:03why we ever evolved such an extraordinary musical instrument
0:57:03 > 0:57:05of such complexity and range.
0:57:05 > 0:57:10So, for our finale, I would like to invite you, and our guests,
0:57:10 > 0:57:11both animal and human,
0:57:11 > 0:57:15to really try and show the full extent of what our voices can do.
0:57:15 > 0:57:18Harry, Katherine, if I can have you back.
0:57:18 > 0:57:22And let me introduce Steven, who is our composer for this evening.
0:57:36 > 0:57:383, 2, 1...
0:57:38 > 0:57:43TUNING FORK DINGS, BUZZING, HISSING, GRUNTS, ELEPHANT TRUMPETS
0:57:46 > 0:57:51HE BEATBOXES WHILE PREVIOUS SOUNDS CONTINUE
0:57:54 > 0:57:57SHE STRUMS WHILE PREVIOUS SOUNDS CONTINUE
0:58:01 > 0:58:07ALL SING "AH" WHILE PREVIOUS SOUNDS CONTINUE