1 00:00:00,500 --> 00:00:06,800 What might be the first human sound aliens ever hear? 2 00:00:06,800 --> 00:00:10,560 VARIED TYPES OF LAUGHTER 3 00:00:11,800 --> 00:00:16,080 It might be the sound of laughter, because laughter is on this record. 4 00:00:16,080 --> 00:00:19,640 It's called The Sounds Of Earth and the real version is attached to the 5 00:00:19,640 --> 00:00:24,480 NASA Voyager spacecraft, the most distant man-made object from earth. 6 00:00:24,480 --> 00:00:27,640 Why would we be trying to greet aliens with laughter? 7 00:00:27,640 --> 00:00:31,240 Well, because laughter is one of mankind's most important sound 8 00:00:31,240 --> 00:00:32,680 communications. 9 00:00:32,680 --> 00:00:36,120 Humans and animals are constantly sending messages to each other in 10 00:00:36,120 --> 00:00:37,400 different ways. 11 00:00:37,400 --> 00:00:38,760 In these lectures, 12 00:00:38,760 --> 00:00:41,600 I'm going to be showing you where this incredible urge to communicate 13 00:00:41,600 --> 00:00:44,160 comes from, and why it's essential 14 00:00:44,160 --> 00:00:47,360 for the survival of so many species on earth. 15 00:00:47,360 --> 00:00:49,600 Welcome to The Language Of Life. 16 00:01:03,760 --> 00:01:06,320 APPLAUSE 17 00:01:15,600 --> 00:01:20,640 Welcome, welcome to the 2017 Royal Institution Christmas Lectures. 18 00:01:20,640 --> 00:01:23,880 I'm Professor Sophie Scott, and I'm a cognitive neuroscientist. 19 00:01:23,880 --> 00:01:27,240 I study the human brain and human communication, 20 00:01:27,240 --> 00:01:28,960 and I've got a message for you, 21 00:01:28,960 --> 00:01:32,400 from one of my favourite research participants, Doug Collins. 22 00:01:33,680 --> 00:01:35,680 Hi, Sophie. Hi, everyone. 23 00:01:35,680 --> 00:01:38,800 I'm Doug and I have the most contagious laugh in the world, 24 00:01:38,800 --> 00:01:40,520 as most people have said. 25 00:01:40,520 --> 00:01:43,680 HE LAUGHS 26 00:01:48,680 --> 00:01:51,120 Laughter's a very basic kind of communication. 27 00:01:51,120 --> 00:01:53,200 It's actually sending a very important message. 28 00:01:53,200 --> 00:01:55,400 It's sending a message to people that you're happy, 29 00:01:55,400 --> 00:01:57,200 you like the people that you're with, 30 00:01:57,200 --> 00:01:59,400 you feel friendly towards them. 31 00:01:59,400 --> 00:02:03,520 It's also, if you noticed there, a very funny kind of sound. 32 00:02:03,520 --> 00:02:07,600 In fact, laughter is a lot more like an animal call than it is like the 33 00:02:07,600 --> 00:02:08,720 speech we normally do. 34 00:02:09,920 --> 00:02:12,320 And in fact, there's a reason for that. 35 00:02:12,320 --> 00:02:16,160 We are not the only animal that laughs, 36 00:02:16,160 --> 00:02:19,080 that sends messages with their laughter, in fact. 37 00:02:19,080 --> 00:02:21,600 Shall we have a go at making some animals laugh right now? 38 00:02:21,600 --> 00:02:25,160 AUDIENCE: Yes. Definitely. I am delighted to introduce to you - 39 00:02:25,160 --> 00:02:28,720 you have to use tiny little non-frightening finger claps - 40 00:02:28,720 --> 00:02:32,720 to introduce you to India Woods and her rat, called Mould. 41 00:02:32,720 --> 00:02:33,720 Big claps. 42 00:02:35,160 --> 00:02:37,000 Hello. Hello, India. 43 00:02:37,000 --> 00:02:39,640 Hello, Mould. I am so excited to meet you. 44 00:02:39,640 --> 00:02:41,760 Fantastic. There we go. 45 00:02:41,760 --> 00:02:43,960 Does Mould laugh ever? 46 00:02:43,960 --> 00:02:45,360 He makes some noises. 47 00:02:45,360 --> 00:02:48,680 Excellent. What do you do normally to make Mould make a noise? 48 00:02:48,680 --> 00:02:51,120 You tickle him. Oh. 49 00:02:51,120 --> 00:02:53,720 OK. Where's the best place to tickle a rat? 50 00:02:53,720 --> 00:02:55,440 Where you tickle a person. 51 00:02:55,440 --> 00:02:57,120 His armpit, on his back. 52 00:02:57,120 --> 00:03:00,120 There we go. Now I don't know about you, 53 00:03:00,120 --> 00:03:03,200 I don't normally feel at my most ticklish 54 00:03:03,200 --> 00:03:06,480 when I'm being watched by about 250 complete strange people 55 00:03:06,480 --> 00:03:08,720 and I've been placed on a little podium. 56 00:03:08,720 --> 00:03:10,520 So I think what we might be doing is, we might 57 00:03:10,520 --> 00:03:13,840 be making it slightly hard for Mould to feel like having a laugh. 58 00:03:13,840 --> 00:03:17,520 I think we have some examples of his laughter from earlier today. 59 00:03:17,520 --> 00:03:18,760 Yes. Can we hear that? 60 00:03:18,760 --> 00:03:22,480 CHIRPY SQUEAKING 61 00:03:25,960 --> 00:03:27,960 You can hear these little chirrupy chirps. 62 00:03:29,600 --> 00:03:33,480 Now that actually is the sound that he's making when he laughs. 63 00:03:33,480 --> 00:03:37,320 We know it's something to do with laughter because rats, just like us, 64 00:03:37,320 --> 00:03:40,040 they laugh when they're tickled. They laugh when they're playing, 65 00:03:40,040 --> 00:03:42,280 they laugh when they want you to play with them. 66 00:03:42,280 --> 00:03:46,280 So it's actually a very important communication sound for rats and for 67 00:03:46,280 --> 00:03:48,480 humans. Thank you very much. 68 00:03:48,480 --> 00:03:51,360 Thank you. Bye-bye, sweetie. 69 00:03:51,360 --> 00:03:57,600 We share a common ancestor with rats going back 65 million years. 70 00:03:57,600 --> 00:04:00,560 So it's possible that laughter really is 71 00:04:00,560 --> 00:04:03,920 a very old communication sound for mammals. 72 00:04:03,920 --> 00:04:08,160 It's possibly certainly one of our earliest communication sounds. 73 00:04:08,160 --> 00:04:12,040 But what would the very first communication sounds have been on earth? 74 00:04:13,160 --> 00:04:15,960 What would have been the first animals to communicate with sounds? 75 00:04:15,960 --> 00:04:18,760 Who would they be? Well, to think about that we're going 76 00:04:18,760 --> 00:04:21,120 to look at these charming specimens. 77 00:04:21,120 --> 00:04:23,480 These are insects. They're actually crickets. 78 00:04:24,560 --> 00:04:29,640 500 million years ago, insects crawled on to the earth, 79 00:04:29,640 --> 00:04:32,360 and they're therefore very good candidates for being the first 80 00:04:32,360 --> 00:04:35,760 animals to use sound for communication in the air. 81 00:04:35,760 --> 00:04:38,800 So, if we look closely at these guys, 82 00:04:38,800 --> 00:04:41,360 we can see they have legs and they have wings. 83 00:04:41,360 --> 00:04:44,520 I can hear they aren't making a sound, so we are going to play in... 84 00:04:46,000 --> 00:04:48,680 ..an example of what it would sound like. 85 00:04:48,680 --> 00:04:51,480 CHIRPING 86 00:04:52,480 --> 00:04:54,200 Can you hear? That chirping sound? 87 00:04:55,600 --> 00:04:57,680 It's actually a very, very basic communication. 88 00:04:57,680 --> 00:05:00,120 What they're saying is "I am here." 89 00:05:00,120 --> 00:05:02,040 "I'm a cricket and I am here." 90 00:05:02,040 --> 00:05:03,640 It's basically a mating call. 91 00:05:03,640 --> 00:05:06,440 The most basic sound you could have, really. "I'm right here. 92 00:05:06,440 --> 00:05:08,160 "Whenever you're ready, I'm here." 93 00:05:08,160 --> 00:05:11,200 So... And they're making it in this fantastic way. 94 00:05:11,200 --> 00:05:13,120 It is simply the best word in science. 95 00:05:13,120 --> 00:05:16,760 They make it via a process called stridulation. 96 00:05:16,760 --> 00:05:18,680 They are stridulating. 97 00:05:18,680 --> 00:05:22,320 And what stridulation means is they're rubbing body parts together. 98 00:05:22,320 --> 00:05:23,880 The way the crickets are doing this is, 99 00:05:23,880 --> 00:05:26,200 they're actually running their wings together. 100 00:05:26,200 --> 00:05:30,720 If we look at a close-up image of the base of a cricket's wing, 101 00:05:30,720 --> 00:05:33,920 you can see it has this very regular notched surface. 102 00:05:33,920 --> 00:05:35,960 When they rub their wings together, 103 00:05:35,960 --> 00:05:39,840 you get a very regular sound coming out of that movement. 104 00:05:39,840 --> 00:05:42,240 There's actually musical instrument that humans use 105 00:05:42,240 --> 00:05:43,920 that makes a sound in a very similar way. 106 00:05:43,920 --> 00:05:46,680 I would like to have a volunteer to have a go at playing this for me. 107 00:05:46,680 --> 00:05:49,280 Can I have you, with the glasses, in the scarf? Thank you very much. 108 00:05:49,280 --> 00:05:50,360 Thank you very much. 109 00:05:57,080 --> 00:05:59,000 Now, what's your name? Alex. 110 00:05:59,000 --> 00:06:00,320 Alex, it's lovely to meet you. 111 00:06:00,320 --> 00:06:03,720 Can I present you with guero? OK. 112 00:06:03,720 --> 00:06:05,720 How do you think you might get a sound out of that? 113 00:06:05,720 --> 00:06:07,560 WHISPERS: It's a bit like the crickets. 114 00:06:09,880 --> 00:06:11,400 Excellent. Go a bit more slowly. 115 00:06:14,680 --> 00:06:16,120 Fantastic. 116 00:06:17,200 --> 00:06:18,880 Top guero playing. 117 00:06:18,880 --> 00:06:21,440 Now you can see there, that, actually, 118 00:06:21,440 --> 00:06:24,400 the regular notches are giving you regularity in the sound. 119 00:06:24,400 --> 00:06:26,520 The crickets aren't just making a noise, 120 00:06:26,520 --> 00:06:29,360 they're making a noise that has some recognisability to it. 121 00:06:29,360 --> 00:06:31,240 It's got some information in it. 122 00:06:31,240 --> 00:06:33,520 It's kind of built in to the structure of the way 123 00:06:33,520 --> 00:06:36,600 it's making the sound at all. Thank you very, very much. 124 00:06:36,600 --> 00:06:38,600 I'll have the guero back. Thank you, Alex. 125 00:06:38,600 --> 00:06:40,920 APPLAUSE 126 00:06:42,800 --> 00:06:45,000 So, Alex was basically stridulating for you there. 127 00:06:45,000 --> 00:06:47,440 She was rubbing two things together to make a sound, 128 00:06:47,440 --> 00:06:48,680 but actually, generally, 129 00:06:48,680 --> 00:06:52,160 whenever you hear a sound, it means something happened, 130 00:06:52,160 --> 00:06:54,360 there was some kind of action in the world. 131 00:06:54,360 --> 00:06:55,960 If there aren't any movements, 132 00:06:55,960 --> 00:06:59,240 if there aren't any actions, there are no sounds. 133 00:06:59,240 --> 00:07:02,680 And we could see there how the regularity in the shape of the guero 134 00:07:02,680 --> 00:07:05,960 or the cricket's wing is giving you regularity to the sound. 135 00:07:05,960 --> 00:07:07,760 That is important for the crickets. 136 00:07:07,760 --> 00:07:10,600 But how do we hear that as a sound? 137 00:07:10,600 --> 00:07:13,760 How do we experience that vibration 138 00:07:13,760 --> 00:07:17,120 as something we can actually perceive? 139 00:07:17,120 --> 00:07:18,360 Well, to think about that, 140 00:07:18,360 --> 00:07:21,560 what we need to do is look at a slightly more simple system. 141 00:07:21,560 --> 00:07:23,200 We are going to look at a tuning fork. 142 00:07:25,880 --> 00:07:27,840 Now this isn't any old tuning fork. 143 00:07:27,840 --> 00:07:30,320 This belonged to John Tyndall, who is - was - 144 00:07:30,320 --> 00:07:32,800 a scientist here at the Royal Institution. 145 00:07:32,800 --> 00:07:36,520 This is 150 years old, and John Tyndall did some amazing work. 146 00:07:36,520 --> 00:07:40,280 He discovered why we see the sky as looking blue and how the greenhouse 147 00:07:40,280 --> 00:07:42,560 effect can lead to global warming. 148 00:07:42,560 --> 00:07:46,200 What I am going to do is hit one of his 150-year-old tuning forks, 149 00:07:46,200 --> 00:07:49,400 and hopefully, we should be able to hear a sound. 150 00:07:49,400 --> 00:07:52,680 MEDIUM-PITCHED DINGING 151 00:07:54,480 --> 00:07:58,160 Now the sound is being made by movements that tuning fork, 152 00:07:58,160 --> 00:08:01,320 but I can't really see those movements as they're moving too quickly. 153 00:08:01,320 --> 00:08:04,480 So, what I'm going to do is turn to a high-speed camera 154 00:08:04,480 --> 00:08:07,880 and we're going to see if we can slow that down and look at it in more detail. 155 00:08:07,880 --> 00:08:10,800 To do this, we're going to need more light because the high-speed camera 156 00:08:10,800 --> 00:08:13,440 needs more light information to get good images. 157 00:08:14,720 --> 00:08:15,640 Thank you. 158 00:08:17,360 --> 00:08:18,800 OK. I'm going to hit it again. 159 00:08:18,800 --> 00:08:21,520 MEDIUM-PITCHED DINGING 160 00:08:21,520 --> 00:08:23,320 You can see there, 161 00:08:23,320 --> 00:08:28,600 I'm hitting it and immediately the tines of the fork start to vibrate. 162 00:08:28,600 --> 00:08:31,480 And that's what's causing the sound to happen. 163 00:08:31,480 --> 00:08:33,480 That's giving us something we can hear. 164 00:08:33,480 --> 00:08:39,360 And it's doing that by causing all the air molecules in the atmosphere 165 00:08:39,360 --> 00:08:42,280 around us to start to vibrate, 166 00:08:42,280 --> 00:08:46,280 and what this sets up is a chain of movements of these air molecules, 167 00:08:46,280 --> 00:08:47,720 vibrating back and forth. 168 00:08:47,720 --> 00:08:52,560 You get waves of air molecules stretching out and being compressed, 169 00:08:52,560 --> 00:08:55,960 and when it reaches our ears, that's what we hear as a sound. 170 00:08:55,960 --> 00:08:58,480 It is very hard to imagine that with the air molecules. 171 00:08:58,480 --> 00:09:02,560 It is easier to imagine with a spring. 172 00:09:02,560 --> 00:09:06,000 So the air, like this spring, is extremely elastic. 173 00:09:08,080 --> 00:09:11,400 What I'm going to do is put a single vibration into the spring. 174 00:09:12,880 --> 00:09:16,720 And you can see how it's being passed along. 175 00:09:18,800 --> 00:09:20,800 Although any one single coil of the spring 176 00:09:20,800 --> 00:09:22,520 is not moving very far at all. 177 00:09:23,880 --> 00:09:28,400 We get that pattern of the waves, of compression, and stretching out. 178 00:09:28,400 --> 00:09:29,400 Thank you very much. 179 00:09:30,480 --> 00:09:32,280 Thank you. 180 00:09:32,280 --> 00:09:35,040 It's easy to see those vibrations in the spring. 181 00:09:35,040 --> 00:09:38,640 We don't really notice it happening in the air around us. 182 00:09:38,640 --> 00:09:41,720 But there is an extremely sensitive photographic technique called 183 00:09:41,720 --> 00:09:46,440 schlieren photography that lets us record the disturbances in the air 184 00:09:46,440 --> 00:09:48,720 as the sound waves are passing through. 185 00:09:51,120 --> 00:09:53,520 So, this is somebody about to clap their hands. 186 00:09:56,000 --> 00:10:00,240 And as their hands contact, look for the sound waves radiating out. 187 00:10:00,240 --> 00:10:04,880 Did you see that pattern of movement radiating out from the hands? 188 00:10:04,880 --> 00:10:08,360 It's been slowed right down, but you can see that was coming from the 189 00:10:08,360 --> 00:10:10,920 source of the sound. 190 00:10:10,920 --> 00:10:14,240 Now, all sounds are made by movements, 191 00:10:14,240 --> 00:10:17,040 but how do our bodies pick them up and hear them? 192 00:10:17,040 --> 00:10:18,960 How do we decode sounds? 193 00:10:18,960 --> 00:10:21,760 Now, tell me, what organ do you use to hear sounds? 194 00:10:21,760 --> 00:10:23,520 Point to it. 195 00:10:23,520 --> 00:10:24,880 Yes, your ears. 196 00:10:24,880 --> 00:10:28,440 Absolutely. In fact, the bits on the outside that we all just pointed to, 197 00:10:28,440 --> 00:10:30,200 that's just the outside of your ear. 198 00:10:30,200 --> 00:10:31,320 That's called the pinna. 199 00:10:31,320 --> 00:10:34,000 And what that does is it's a funnel 200 00:10:34,000 --> 00:10:37,000 for pointing all these air vibrations 201 00:10:37,000 --> 00:10:41,440 down towards the real ear, which is actually located down, 202 00:10:41,440 --> 00:10:43,680 tucked away inside your head. 203 00:10:43,680 --> 00:10:47,200 And what this is doing, it's trying to turn the vibrations that are 204 00:10:47,200 --> 00:10:48,840 sending sound over to you 205 00:10:48,840 --> 00:10:50,680 into something that the brain can perceive. 206 00:10:50,680 --> 00:10:55,280 And what the brain wants is the information in an electrical form. 207 00:10:55,280 --> 00:10:57,560 Your brain deals with electrical signals. 208 00:10:59,400 --> 00:11:01,160 So how do we turn... 209 00:11:01,160 --> 00:11:05,400 these vibrations of the air molecules into an electrical signal? 210 00:11:05,400 --> 00:11:08,280 Well, this is a demonstration of that at work. 211 00:11:08,280 --> 00:11:11,760 So we have air molecules moving down and it's funnelled in 212 00:11:11,760 --> 00:11:14,280 by your pinna towards the eardrum. 213 00:11:14,280 --> 00:11:16,920 And what you have at the eardrum is just like a drum. 214 00:11:16,920 --> 00:11:20,960 It's vibrating when the air molecules push against it 215 00:11:20,960 --> 00:11:23,880 and then transmits that pattern of vibration 216 00:11:23,880 --> 00:11:27,960 through the tiny little bones, the smallest bones in your body. 217 00:11:27,960 --> 00:11:32,360 And then that is sending a vibration into one end of what's called the 218 00:11:32,360 --> 00:11:36,920 cochlea. And the cochlea is a fluid-filled tube 219 00:11:36,920 --> 00:11:39,960 and that fluid starts to move with the vibrations. 220 00:11:39,960 --> 00:11:42,960 So, it's all still physical movement, 221 00:11:42,960 --> 00:11:46,960 and in the cochlea, there are these tiny little cells called hair cells. 222 00:11:46,960 --> 00:11:49,040 And they start to bob up and down. 223 00:11:49,040 --> 00:11:51,720 And they have small filaments called the hairs. 224 00:11:51,720 --> 00:11:53,320 When those move... 225 00:11:53,320 --> 00:11:55,800 When the whole thing bobs up and down like that, 226 00:11:55,800 --> 00:11:59,360 that is what sends an electrical signal to your brain. 227 00:11:59,360 --> 00:12:01,600 So, the entire ear is a machine 228 00:12:01,600 --> 00:12:03,800 for turning the vibrations of the air into 229 00:12:03,800 --> 00:12:06,280 something your brain can hear as sound. 230 00:12:06,280 --> 00:12:08,400 And, of course, if anything goes wrong 231 00:12:08,400 --> 00:12:10,000 with this entire chain of events, 232 00:12:10,000 --> 00:12:11,960 you'll have a problem with your hearing. 233 00:12:11,960 --> 00:12:14,760 The ear has moving parts and those moving parts can break. 234 00:12:16,520 --> 00:12:18,800 So, communication with sound 235 00:12:18,800 --> 00:12:21,440 is about creating movement of molecules, 236 00:12:21,440 --> 00:12:26,480 which another creature can pick up, detect and experience as sound. 237 00:12:28,280 --> 00:12:31,280 However, we're living in quite a noisy world. 238 00:12:31,280 --> 00:12:34,640 We only tend to notice sounds that we can hear. 239 00:12:34,640 --> 00:12:37,320 But there are lots and lots of communication sounds we can't hear. 240 00:12:38,640 --> 00:12:41,920 So, we've got an example here for another tuning fork. 241 00:12:41,920 --> 00:12:45,520 Now this tuning fork is much larger than the one I showed you before. 242 00:12:46,920 --> 00:12:51,280 This one will vibrate at a pitch much too low for us to hear. 243 00:12:52,520 --> 00:12:55,720 So, how do I convince you that something's making a sound 244 00:12:55,720 --> 00:12:57,080 that you can't hear? 245 00:12:57,080 --> 00:12:59,520 Well, I suppose I could just ask you to believe me, 246 00:12:59,520 --> 00:13:01,840 but let's try and do it with a demonstration. 247 00:13:01,840 --> 00:13:06,360 What we're going to do here is we're going to put sound into the tuning 248 00:13:06,360 --> 00:13:08,200 fork through this loudspeaker. 249 00:13:09,840 --> 00:13:12,960 You'll hear the sound at first cos it will still be in a range where we 250 00:13:12,960 --> 00:13:14,240 can hear sounds. 251 00:13:14,240 --> 00:13:17,400 And then it will drop down so that we can't really hear it at all. 252 00:13:17,400 --> 00:13:20,800 But we will start to see the tuning fork itself begin to move. 253 00:13:22,920 --> 00:13:25,080 OK, you can put your hands over your ears for this. 254 00:13:25,080 --> 00:13:26,760 Right. 255 00:13:26,760 --> 00:13:28,720 LOW-PITCHED HUM 256 00:13:28,720 --> 00:13:30,480 Still hear that? Still hear that? 257 00:13:32,160 --> 00:13:33,840 PITCH LOWERS Going down. 258 00:13:35,160 --> 00:13:37,160 PITCH LOWERS AND BECOMES INAUDIBLE 259 00:13:37,160 --> 00:13:41,160 Now, if you look, you can see the loudspeaker moving. 260 00:13:41,160 --> 00:13:42,760 There are sounds coming out of that. 261 00:13:42,760 --> 00:13:45,080 And it's starting to vibrate the tuning fork. 262 00:13:45,080 --> 00:13:48,280 So there's energy coming out of here we can't hear. 263 00:13:51,360 --> 00:13:52,920 That's called infra-sound, 264 00:13:52,920 --> 00:13:55,800 sound that's simply too low for us to be able to detect. 265 00:13:57,080 --> 00:14:01,120 And infra-sounds can be exploited by animals, 266 00:14:01,120 --> 00:14:03,640 normally animals much larger than us. 267 00:14:03,640 --> 00:14:05,920 Animals, in fact, that I'm very fond of. 268 00:14:05,920 --> 00:14:07,200 Elephants. 269 00:14:07,200 --> 00:14:11,360 Now, I'm very sorry to say I haven't got an elephant to show you. 270 00:14:11,360 --> 00:14:13,760 We can't get them in the lift. 271 00:14:15,360 --> 00:14:17,560 So I went to ZSL, Whipsnade Zoo, 272 00:14:17,560 --> 00:14:21,600 to meet qualified elephant keeper Ben Abbott and find out more. 273 00:14:29,240 --> 00:14:32,560 So, the very low-pitch, low-frequency sounds the elephants make, 274 00:14:32,560 --> 00:14:34,400 it gets called infra-sound. 275 00:14:34,400 --> 00:14:37,320 Yep. Are there particular situations in which they use that? 276 00:14:37,320 --> 00:14:39,760 Does it work better in some environments than others? 277 00:14:39,760 --> 00:14:41,400 Yeah, I mean, generally speaking, 278 00:14:41,400 --> 00:14:43,040 the infra-sound an elephant will use 279 00:14:43,040 --> 00:14:45,520 because they can communicate over such vast distances. 280 00:14:45,520 --> 00:14:48,680 So, when a herd of elephants is travelling, they spread out, 281 00:14:48,680 --> 00:14:52,440 which could be over, say, 50-250 metres apart. 282 00:14:52,440 --> 00:14:55,560 Right. And if you can imagine one's all the way over there and one's here. 283 00:14:55,560 --> 00:14:58,040 And one wants to say, we're going this way, just for an example, 284 00:14:58,040 --> 00:15:00,160 they will communicate through low frequency. 285 00:15:00,160 --> 00:15:03,400 And so, is there evidence that they're picking up all of this sound 286 00:15:03,400 --> 00:15:06,920 just with their ears or is there any other way that they're detecting that infra-sound? 287 00:15:06,920 --> 00:15:08,880 Yes, so technically there's two ways, really, 288 00:15:08,880 --> 00:15:10,240 that elephants tend to favour. 289 00:15:10,240 --> 00:15:12,280 I mean, obviously, they have got very big ears. 290 00:15:12,280 --> 00:15:14,280 The other way they pick up is through their feet. 291 00:15:14,280 --> 00:15:16,680 They've got a big, squidgy cushion behind their toenails, 292 00:15:16,680 --> 00:15:19,440 so when they walk it sort of sucks up and when they put their foot on 293 00:15:19,440 --> 00:15:21,320 the floor, it increases the surface area. 294 00:15:21,320 --> 00:15:24,240 Now, if they're walking over vast distances, they can actually pick up 295 00:15:24,240 --> 00:15:26,880 these vibrations, so by putting their foot flat on the floor, 296 00:15:26,880 --> 00:15:30,520 they feel the vibrations, whatever the communication may be, through infra-sound. 297 00:15:30,520 --> 00:15:33,120 APPLAUSE 298 00:15:36,600 --> 00:15:39,280 So, the elephants are really hearing the sound in two ways. 299 00:15:39,280 --> 00:15:41,280 They're experiencing it in two ways. 300 00:15:41,280 --> 00:15:44,560 They hear it as a sound and they're also picking it up by feeling it in 301 00:15:44,560 --> 00:15:48,560 their feet. And the real advantage of that is the low-frequency sounds 302 00:15:48,560 --> 00:15:51,960 pass very, very well through solid things like the ground. 303 00:15:51,960 --> 00:15:55,000 And that means that actually the low-frequency sounds that they're 304 00:15:55,000 --> 00:15:58,040 making with the infra-sound can travel a long way and be detected 305 00:15:58,040 --> 00:16:00,560 through another elephant's feet quite some distance away, 306 00:16:00,560 --> 00:16:03,120 in a way that a low-frequency sound might struggle to be carried 307 00:16:03,120 --> 00:16:04,920 by the air. 308 00:16:04,920 --> 00:16:07,040 This, just one advantage of sound. 309 00:16:07,040 --> 00:16:12,120 And, in fact, sound is an incredibly powerful way, efficient way, 310 00:16:12,120 --> 00:16:14,640 of sharing communication information. 311 00:16:14,640 --> 00:16:16,840 It's very fast-moving. 312 00:16:16,840 --> 00:16:19,480 The speed of sound is around 300 metres per second, 313 00:16:19,480 --> 00:16:22,720 so you can get a signal out there very quickly. 314 00:16:22,720 --> 00:16:25,680 It works in the dark. It works if something's behind you. 315 00:16:25,680 --> 00:16:28,000 It works if your eyes are closed. 316 00:16:28,000 --> 00:16:30,640 When you hear a sound, it means an event has happened. 317 00:16:30,640 --> 00:16:32,320 It can suddenly start. 318 00:16:32,320 --> 00:16:35,480 This is one of the reasons why, throughout nature, 319 00:16:35,480 --> 00:16:39,680 when an animal wants to send an alarm signal, if it can do, 320 00:16:39,680 --> 00:16:41,120 it will do so with sound. 321 00:16:42,440 --> 00:16:45,880 But actually, we don't only use sound for very, very basic things 322 00:16:45,880 --> 00:16:47,720 like alarm calls. 323 00:16:47,720 --> 00:16:51,040 Because once you've got a sound, you can vary how loud it is. 324 00:16:51,040 --> 00:16:52,600 You can vary what its pitch is. 325 00:16:52,600 --> 00:16:54,400 You can vary its rhythm. 326 00:16:54,400 --> 00:16:56,240 And you can have interactions with sounds. 327 00:16:56,240 --> 00:16:58,560 You can have conversations with sounds. 328 00:16:58,560 --> 00:17:02,720 And I've got quite a surprising example of one of those conversations now. 329 00:17:02,720 --> 00:17:05,200 Going to play you a sound, see if you can recognise it. 330 00:17:05,200 --> 00:17:08,800 HIGH-PITCHED BUZZING 331 00:17:10,440 --> 00:17:13,800 Anyone know what that is? Yep. 332 00:17:13,800 --> 00:17:15,280 A vacuum cleaner. 333 00:17:15,280 --> 00:17:17,280 It's not a vacuum cleaner. 334 00:17:17,280 --> 00:17:20,800 We're not quite having conversations with those yet. Any other guesses? 335 00:17:20,800 --> 00:17:22,360 Yes. Yep. Mosquito. 336 00:17:22,360 --> 00:17:23,640 It's a mosquito. 337 00:17:23,640 --> 00:17:26,920 Yes. One of the horrible things that you hear flying around if you're 338 00:17:26,920 --> 00:17:29,840 somewhere warm enough to support mosquitoes. 339 00:17:29,840 --> 00:17:35,000 Unlike vacuum cleaners, mosquitoes make this sound and... 340 00:17:35,000 --> 00:17:38,040 We don't quite know... I always assumed they were kind of saying, 341 00:17:38,040 --> 00:17:40,240 "I'm in your hotel room and I'm going to bite you." 342 00:17:40,240 --> 00:17:44,200 But it turns out they're sending a rather more complex signal than that. 343 00:17:44,200 --> 00:17:46,440 And to tell us more about this, I'd like to introduce, 344 00:17:46,440 --> 00:17:47,960 from the University of Greenwich, 345 00:17:47,960 --> 00:17:50,840 Professor Gay Gibson and Lionel Feugere. 346 00:17:56,920 --> 00:17:59,600 How are mosquitoes making that sound? 347 00:17:59,600 --> 00:18:02,680 That sound is just purely the sound that's made when they beat their 348 00:18:02,680 --> 00:18:05,440 wings to fly. OK. So when they're flying, it's the sound they make? 349 00:18:05,440 --> 00:18:08,680 Exactly. Yep. And is that the whole story, is that the only thing that's going on? 350 00:18:08,680 --> 00:18:10,600 It's not the whole story, no. 351 00:18:10,600 --> 00:18:14,640 We've known for a long time that male mosquitoes can hear the sound 352 00:18:14,640 --> 00:18:16,720 of a female flying by. 353 00:18:16,720 --> 00:18:19,880 So we know it's got something to do with mating, but we didn't know the 354 00:18:19,880 --> 00:18:23,200 whole story until we investigated it a little bit further. 355 00:18:23,200 --> 00:18:25,160 OK. And is that the set-up that we've got here? 356 00:18:25,160 --> 00:18:28,440 Yeah, that's what we've got here. Would you like to take us through it? Yes, sure. 357 00:18:28,440 --> 00:18:31,200 So, we all know that sound, 358 00:18:31,200 --> 00:18:33,920 that irritating sound that mosquitoes make. 359 00:18:33,920 --> 00:18:41,480 And we can study it more in depth by recording the sound that they make. 360 00:18:41,480 --> 00:18:45,040 And so we've done that here, we've brought in the apparatus that we used. 361 00:18:45,040 --> 00:18:48,680 AMPLIFIED BUZZING That's a mosquito that's flying. 362 00:18:48,680 --> 00:18:50,400 So what we can see here, 363 00:18:50,400 --> 00:18:53,080 they are two mosquitoes and they are held just with a little bit of 364 00:18:53,080 --> 00:18:55,280 beeswax on the end of a... 365 00:18:55,280 --> 00:18:56,960 Of a very fine, fine wire. 366 00:18:56,960 --> 00:19:00,560 OK. And then on top of that, this yellow box there, 367 00:19:00,560 --> 00:19:02,600 that's an old-fashioned 368 00:19:02,600 --> 00:19:06,440 phonograph needle that we used to listen to records with. 369 00:19:06,440 --> 00:19:08,040 And they're still very useful, 370 00:19:08,040 --> 00:19:11,440 they pick up very fine vibrations from that wire, 371 00:19:11,440 --> 00:19:14,560 to listen in on the mosquitoes' wing beats. 372 00:19:14,560 --> 00:19:17,840 OK, so at the moment, they're not flying because... 373 00:19:17,840 --> 00:19:21,120 That's right. So when they've got a piece of paper under their feet there, 374 00:19:21,120 --> 00:19:23,720 they think they're on the ground, so they fold their wings back. 375 00:19:23,720 --> 00:19:26,520 But if someone could help us demonstrate this... 376 00:19:26,520 --> 00:19:27,960 Yeah, we need a volunteer. 377 00:19:27,960 --> 00:19:31,320 Can I have...? Can I have you there with the checked shirt? 378 00:19:31,320 --> 00:19:33,280 And the dark jacket. Thank you very much. 379 00:19:38,320 --> 00:19:40,360 What's your name? Sachin. 380 00:19:40,360 --> 00:19:43,280 Sachin. Now, Sachin, I need to emphasise to you, 381 00:19:43,280 --> 00:19:46,240 the importance of being super gentle with the mosquitoes. 382 00:19:46,240 --> 00:19:49,640 OK? We don't want to hurt them. No. Thank you very much, Sachin. 383 00:19:49,640 --> 00:19:51,600 Now, Gay's going to tell you exactly what to do. 384 00:19:51,600 --> 00:19:53,120 OK, if you come around here. 385 00:19:53,120 --> 00:19:56,000 Do you want to step forward? I think you can see this little piece of 386 00:19:56,000 --> 00:19:57,800 white paper here. So, in a minute, 387 00:19:57,800 --> 00:19:59,640 I'm going to ask you to take the paper away 388 00:19:59,640 --> 00:20:03,000 and then we're going to listen the sound that we hear. 389 00:20:03,000 --> 00:20:06,960 So, this one is a female mosquito sound. 390 00:20:06,960 --> 00:20:09,920 Could you please gently take that piece of paper away? 391 00:20:09,920 --> 00:20:12,240 MEDIUM-PITCHED BUZZING 392 00:20:12,240 --> 00:20:13,880 Oops. 393 00:20:13,880 --> 00:20:17,120 And she's immediately making a sound. 394 00:20:17,120 --> 00:20:19,960 LOW-PITCHED BUZZING That's a female wing-beat frequency. 395 00:20:19,960 --> 00:20:21,720 OK. Can we hear the male? 396 00:20:21,720 --> 00:20:25,280 Yeah. Let's do that. I'll put this one back myself. 397 00:20:27,240 --> 00:20:29,520 Would you like to take the male one away? 398 00:20:29,520 --> 00:20:31,080 Listen to this one, what's different? 399 00:20:31,080 --> 00:20:35,280 HIGH-PITCHED BUZZING 400 00:20:35,280 --> 00:20:39,280 It does sound very different, doesn't it? Yeah. Much higher tone. 401 00:20:39,280 --> 00:20:42,520 OK. Males have the high voices and females have the low voices. 402 00:20:43,680 --> 00:20:47,200 But the more interesting thing is what happens when they can both hear 403 00:20:47,200 --> 00:20:48,920 each other. 404 00:20:48,920 --> 00:20:52,040 So we're going to turn these mosquitoes off now. 405 00:20:53,920 --> 00:20:56,160 OK. So, now we're going to take them both off. 406 00:20:57,160 --> 00:20:59,120 Yes. 407 00:20:59,120 --> 00:21:01,840 OK. Listen what happens when they can hear each other. 408 00:21:01,840 --> 00:21:04,080 LOW-PITCHED BUZZING That's the female. 409 00:21:04,080 --> 00:21:07,520 HIGH-PITCHED BUZZING There's the male. 410 00:21:07,520 --> 00:21:10,120 BUZZING HARMONISES 411 00:21:11,200 --> 00:21:14,400 It sounds like they're bringing their voices together. 412 00:21:14,400 --> 00:21:18,520 They are indeed. They're going up and down a little bit. 413 00:21:18,520 --> 00:21:20,920 Hang on. Is this a duet? 414 00:21:22,720 --> 00:21:24,520 It is exactly a duet. 415 00:21:24,520 --> 00:21:29,960 And they can make this interaction between each other to help identify, 416 00:21:29,960 --> 00:21:32,840 "Are you the right species? Are you the one I want to mate with?" 417 00:21:32,840 --> 00:21:36,720 So, that's the way they communicate, whether or not it's a good match. 418 00:21:36,720 --> 00:21:38,720 It's a love song. I can't believe it. 419 00:21:38,720 --> 00:21:41,440 Sachin, thank you very much. Thank you. Fantastic. 420 00:21:44,880 --> 00:21:46,680 Beautiful work. 421 00:21:46,680 --> 00:21:48,240 We can look at this on the screen. 422 00:21:50,480 --> 00:21:54,200 So, Gay, I think you've got a visual example of this, is that right? 423 00:21:54,200 --> 00:21:56,920 Yeah, we have a recording we made earlier. 424 00:21:56,920 --> 00:22:00,320 So, this is a visual representation of that song - that duet - 425 00:22:00,320 --> 00:22:02,720 that you recorded earlier. Can you talk us through this? 426 00:22:02,720 --> 00:22:04,800 Yeah, certainly. So, here are the two mosquitoes. 427 00:22:04,800 --> 00:22:07,920 This is the female going along at a steady frequency. 428 00:22:07,920 --> 00:22:11,360 And here's the male. You can see he's going up and then down. 429 00:22:11,360 --> 00:22:14,080 And then... Can we hear that? We can hear how that sounds. 430 00:22:14,080 --> 00:22:18,920 BUZZING HARMONISES 431 00:22:18,920 --> 00:22:21,240 PITCH OF BUZZING LOWERS Dipping right down. OK. 432 00:22:21,240 --> 00:22:24,320 And then they're coming towards the same pitch. 433 00:22:24,320 --> 00:22:26,440 Yeah, they're having a little dialogue. 434 00:22:27,800 --> 00:22:29,640 It really is in harmony, isn't it? 435 00:22:34,760 --> 00:22:37,640 Till finally they settle on the harmony. 436 00:22:37,640 --> 00:22:40,880 That's extraordinary. I don't know if I'm emotionally ready for really 437 00:22:40,880 --> 00:22:42,800 romantic mosquitoes. 438 00:22:42,800 --> 00:22:46,200 What they're doing is producing a song the whole time. 439 00:22:46,200 --> 00:22:49,880 The whole time they're flying, they're doing this harmonisation. 440 00:22:49,880 --> 00:22:51,600 Why can't they just look at each other? 441 00:22:51,600 --> 00:22:53,520 Why do they need to do this? 442 00:22:53,520 --> 00:22:57,400 Well, they need to use sound because most mosquitoes are very nocturnal, 443 00:22:57,400 --> 00:22:59,240 so they don't have very good vision, 444 00:22:59,240 --> 00:23:02,680 but sound will carry much further than vision. 445 00:23:02,680 --> 00:23:05,320 And they're not just emitting the sound at each other, 446 00:23:05,320 --> 00:23:08,720 they're actually changing their sound till they sound similar. 447 00:23:08,720 --> 00:23:09,960 Yes, that's right - yes. 448 00:23:09,960 --> 00:23:12,640 They need to keep flying to be getting anywhere, but 449 00:23:12,640 --> 00:23:14,560 then they're also simultaneously, 450 00:23:14,560 --> 00:23:17,280 independently changing this frequency 451 00:23:17,280 --> 00:23:21,240 in order to come to a decision to mate with each other. Amazing. 452 00:23:21,240 --> 00:23:23,680 Thank you very, very much, Gay. Thank you very much, Lionel. 453 00:23:33,440 --> 00:23:36,000 Animals aren't just using sounds to signal alarm, 454 00:23:36,000 --> 00:23:37,840 they're not just using it for mating calls. 455 00:23:37,840 --> 00:23:41,880 You can see here they're using sound in a really complex, nuanced way, 456 00:23:41,880 --> 00:23:43,880 for a real conversation. 457 00:23:43,880 --> 00:23:45,920 And, for most mosquitoes, 458 00:23:45,920 --> 00:23:49,040 it's incredibly important that they can manage this. 459 00:23:49,040 --> 00:23:51,000 It's vital to their mating success. 460 00:23:52,360 --> 00:23:56,240 So, we've seen stridulation being an excellent way of making sound. 461 00:23:56,240 --> 00:24:00,400 We've seen beating wings as another way of making sound. 462 00:24:00,400 --> 00:24:04,320 Another way that you often find sound being produced and controlled 463 00:24:04,320 --> 00:24:09,880 in the animal world is by using breath, controlling breath. 464 00:24:09,880 --> 00:24:14,920 Now, I've got some examples here of creatures who are very good at using 465 00:24:14,920 --> 00:24:16,400 their breath to make a sound. 466 00:24:16,400 --> 00:24:19,680 These guys are Madagascan hissing cockroaches. 467 00:24:19,680 --> 00:24:23,080 What they do is they use breath to produce an alarm call. 468 00:24:23,080 --> 00:24:25,160 And I need a volunteer 469 00:24:25,160 --> 00:24:30,440 who is simultaneously extremely brave and also going to be very, 470 00:24:30,440 --> 00:24:33,320 very gentle with a Madagascan hissing cockroach. 471 00:24:33,320 --> 00:24:35,040 Come and pick one up for me. 472 00:24:35,040 --> 00:24:37,120 Let me have a look. Let me have a look. 473 00:24:37,120 --> 00:24:39,800 Can I have you in the red jumper? 474 00:24:39,800 --> 00:24:41,600 Thank you very much. Are you feeling brave? 475 00:24:43,080 --> 00:24:44,000 Thank you very much. 476 00:24:45,240 --> 00:24:48,160 Now, what's your name? Orla. Orla? Lovely to meet you, Orla. 477 00:24:48,160 --> 00:24:50,360 Would you want to have a go at picking one of these 478 00:24:50,360 --> 00:24:53,840 up for me? What we're going to do is see what sound they make when you do 479 00:24:53,840 --> 00:24:57,000 that. OK. So, you and I need to be quiet. 480 00:24:57,000 --> 00:25:02,320 I'll put the mic in. You reach in and very gently pick one up. 481 00:25:07,000 --> 00:25:09,640 HISSING 482 00:25:18,480 --> 00:25:21,280 Amazing. Thank you very much, Orla. Thank you. 483 00:25:26,520 --> 00:25:31,000 So, I'm going to suggest that we bring out a really qualified wrangler of 484 00:25:31,000 --> 00:25:32,760 cockroaches to go in in a bit more detail. 485 00:25:32,760 --> 00:25:34,520 We're going to have a look at these guys 486 00:25:34,520 --> 00:25:37,240 and actually how they make these sounds. Is that OK? This is Ed. 487 00:25:40,920 --> 00:25:43,600 HISSING 488 00:25:43,600 --> 00:25:45,160 OK. 489 00:25:45,160 --> 00:25:47,720 So, if we look close up... 490 00:25:50,120 --> 00:25:52,520 So, this is just a cockroach that Ed's holding up to the camera. 491 00:25:53,720 --> 00:25:54,960 We can see along here... 492 00:25:56,560 --> 00:25:58,240 ..those are spiracles. 493 00:25:58,240 --> 00:26:01,680 That's how insects get air into their body for respiration, 494 00:26:01,680 --> 00:26:04,240 how they're getting oxygen in and carbon dioxide out. 495 00:26:04,240 --> 00:26:06,440 It just diffuses into the holes. 496 00:26:06,440 --> 00:26:11,320 What these cockroaches can do is they can close all but one of these 497 00:26:11,320 --> 00:26:15,680 spiracles and then press that abdomen in to force all of the air 498 00:26:15,680 --> 00:26:19,800 out through just one hole and that's how we get this TSSSSSSS sound. 499 00:26:21,560 --> 00:26:23,120 OK. 500 00:26:23,120 --> 00:26:24,720 Coming out from the side here. 501 00:26:24,720 --> 00:26:25,720 OK. 502 00:26:26,880 --> 00:26:28,240 Thank you very much, Ed. 503 00:26:39,360 --> 00:26:42,560 Now we, like cockroaches, move air around to breathe. 504 00:26:42,560 --> 00:26:44,120 But we do it slightly differently. 505 00:26:44,120 --> 00:26:46,520 We're not letting air permeate through our spiracles, 506 00:26:46,520 --> 00:26:50,160 we draw air in and out of our lungs and that's how we breathe. 507 00:26:50,160 --> 00:26:52,000 And we, like lots of other mammals, 508 00:26:52,000 --> 00:26:55,320 have turned that into a way of making a sound. 509 00:26:55,320 --> 00:26:58,400 Now we don't make a noisy, hissing sound, 510 00:26:58,400 --> 00:27:01,480 we produce a rather more regular vibration sound, 511 00:27:01,480 --> 00:27:03,880 a bit more like the cricket's wings. 512 00:27:03,880 --> 00:27:06,240 Now, how do we make this vibration? 513 00:27:06,240 --> 00:27:08,440 Can you all just put your hands on your throats for me? 514 00:27:08,440 --> 00:27:12,360 And now go, TSSSSSSS, like the hissing cockroach. 515 00:27:12,360 --> 00:27:14,440 HISSING 516 00:27:14,440 --> 00:27:16,360 I can't feel anything happening here. 517 00:27:16,360 --> 00:27:19,720 Now try that again but go... ZZZZZZ, like you're saying zoo. 518 00:27:19,720 --> 00:27:22,800 BUZZING 519 00:27:22,800 --> 00:27:24,560 What can you feel? 520 00:27:24,560 --> 00:27:27,440 A vibration. Exactly. You feel a vibration in your throat. 521 00:27:27,440 --> 00:27:30,520 Now, that's actually the source of the sounds that we're using. 522 00:27:30,520 --> 00:27:33,840 It's in what's called the voice box, also called the larynx. 523 00:27:33,840 --> 00:27:37,160 Inside that, there are two pieces of tissue called the vocal folds and we 524 00:27:37,160 --> 00:27:39,400 vibrate those to make that sound. 525 00:27:39,400 --> 00:27:42,040 Now, let's see that larynx in action. 526 00:27:42,040 --> 00:27:44,760 I'd now like to welcome Professor Martin Birchall 527 00:27:44,760 --> 00:27:48,400 and willing soprano singer Francesca Chiejina. Fantastic! 528 00:27:58,880 --> 00:28:02,600 Can I ask you to sit down? 529 00:28:02,600 --> 00:28:05,000 And all of this is being operated by Idris. 530 00:28:05,000 --> 00:28:08,640 Martin, you're our consultant head-and-neck surgeon at UCLH. 531 00:28:08,640 --> 00:28:12,840 Yep. And you, Francesca, are a soprano singer from the 532 00:28:12,840 --> 00:28:15,320 Royal Opera House Jet Parker Young Artists' Programme. 533 00:28:15,320 --> 00:28:18,680 What we're going to do is use this rather alarmingly large 534 00:28:18,680 --> 00:28:22,000 piece of equipment to have a look at a larynx in action, I understand. 535 00:28:22,000 --> 00:28:24,280 We are. So, what actually is this? 536 00:28:24,280 --> 00:28:27,720 So, this is equipment that we use in the clinic and the hospitals every 537 00:28:27,720 --> 00:28:31,520 day. It's a nasal endoscope and we use it for looking at the 538 00:28:31,520 --> 00:28:33,080 throat and diagnosing people. 539 00:28:33,080 --> 00:28:35,120 OK. Can we actually do that now? 540 00:28:35,120 --> 00:28:36,400 Absolutely, we can. OK. 541 00:28:36,400 --> 00:28:38,320 Are you ready for this? Yes. 542 00:28:38,320 --> 00:28:40,080 Now, what's the actual device like? 543 00:28:40,080 --> 00:28:43,000 Yeah. So, what we've got here, there's three bits to this. 544 00:28:43,000 --> 00:28:45,840 We've got a light source here, we've got a processor, 545 00:28:45,840 --> 00:28:48,880 and we've got a strobe light generator. 546 00:28:48,880 --> 00:28:50,280 This itself is the endoscope. 547 00:28:50,280 --> 00:28:52,560 In the old days, these used to have... 548 00:28:52,560 --> 00:28:54,480 They were fibre optics. 549 00:28:54,480 --> 00:28:57,720 And so you'd get an image that was made up like the eye of an insect. 550 00:28:57,720 --> 00:29:01,640 Nowadays, we're fortunate enough to have very high-definition cameras, 551 00:29:01,640 --> 00:29:04,440 much better than the ones in your phones, right on the ends, 552 00:29:04,440 --> 00:29:07,000 so we can see right inside. OK. 553 00:29:07,000 --> 00:29:09,240 Can we do that now? Is that all right with you? Yes. 554 00:29:09,240 --> 00:29:11,760 So, we're going to drop the endoscope down actually 555 00:29:11,760 --> 00:29:13,600 to look right at Francesca's larynx. 556 00:29:13,600 --> 00:29:15,920 That's precisely what we're going to do. 557 00:29:15,920 --> 00:29:18,520 You'll be able to see the image on the screen there. 558 00:29:18,520 --> 00:29:21,120 OK. Thank you very much. So, breathe gently through your nose, 559 00:29:21,120 --> 00:29:22,800 relax your shoulders. 560 00:29:22,800 --> 00:29:24,440 This is going to tickle a little bit. 561 00:29:24,440 --> 00:29:26,360 Could I see the screen, Idris? 562 00:29:26,360 --> 00:29:28,920 Thank you very much. 563 00:29:28,920 --> 00:29:32,000 So, is that the back of the nose? No, we're actually going through the nose. 564 00:29:32,000 --> 00:29:34,320 The nose is very important for the voice, actually. 565 00:29:34,320 --> 00:29:36,360 It's an air-conditioning device. 566 00:29:36,360 --> 00:29:38,560 So, it warms, humidifies, 567 00:29:38,560 --> 00:29:40,360 filters the air that we breathe 568 00:29:40,360 --> 00:29:44,000 to make sure everything we breathe in is nice and clean. That's why 569 00:29:44,000 --> 00:29:47,000 it's bad to breathe through your mouth. 570 00:29:47,000 --> 00:29:49,120 And that's the larynx. 571 00:29:49,120 --> 00:29:52,800 It is. What we're looking at there, it's a very alien-looking thing, 572 00:29:52,800 --> 00:29:55,600 isn't it, is the larynx, in the middle of the view there. 573 00:29:55,600 --> 00:29:59,080 The vocal cords are the two grey things moving in and out, 574 00:29:59,080 --> 00:30:01,080 forming a V-shape in the centre. 575 00:30:01,080 --> 00:30:04,280 The big, floppy thing is called the epiglottis, it's like a trap door. 576 00:30:04,280 --> 00:30:07,000 It stops food and drink going down the wrong way. 577 00:30:07,000 --> 00:30:10,800 And the two round things towards the back are called arytenoids - 578 00:30:10,800 --> 00:30:14,120 they're bones that move the vocal cords in and out. 579 00:30:14,120 --> 00:30:17,120 Francesca, would you feel OK just to sing a note for us? 580 00:30:17,120 --> 00:30:18,080 OK. 581 00:30:19,640 --> 00:30:22,560 Any note? Absolutely. Go for it. 582 00:30:22,560 --> 00:30:27,600 SHE SINGS MEDIUM-PITCHED NOTE 583 00:30:34,120 --> 00:30:36,840 So, I could hear and see the larynx came together. 584 00:30:36,840 --> 00:30:38,280 I couldn't see it moving. 585 00:30:38,280 --> 00:30:41,120 You'll see it now. We'll now switch to a different light source that's 586 00:30:41,120 --> 00:30:45,600 going to flash light out of phase with the fundamental frequency of 587 00:30:45,600 --> 00:30:48,280 the sound she makes. Basically, it's strobing, 588 00:30:48,280 --> 00:30:51,880 like in discos when I was a young man, a long time ago. 589 00:30:51,880 --> 00:30:53,600 It slows down movement. 590 00:30:53,600 --> 00:30:55,160 You should see this here. 591 00:30:55,160 --> 00:30:59,160 So, if you'd like to make a slightly higher-frequency sound, Francesca. 592 00:30:59,160 --> 00:31:03,360 SHE SINGS HIGH-PITCHED NOTE 593 00:31:08,960 --> 00:31:10,800 Very good. Fantastic. I could feel it. 594 00:31:10,800 --> 00:31:13,160 Well done! Now, could you do a glissando for us? 595 00:31:13,160 --> 00:31:15,840 From as low as you can, to as high as you can. 596 00:31:15,840 --> 00:31:20,720 OK. It feels so weird. OK. 597 00:31:22,480 --> 00:31:33,320 SHE SINGS GLISSANDO 598 00:31:33,320 --> 00:31:37,600 Beautiful. So, you can see the vocal cords lengthening and shortening. 599 00:31:51,440 --> 00:31:55,960 How was Francesca able to move her vocal folds so very quickly? 600 00:31:55,960 --> 00:31:58,680 She's moving them around 2,000 times a second, 601 00:31:58,680 --> 00:32:01,160 much too fast for us to be able to see. 602 00:32:01,160 --> 00:32:03,000 Now, how fast can you move your body? 603 00:32:04,400 --> 00:32:09,160 Clap your hands for me. I want to see how quickly you can clap your hands together. 604 00:32:09,160 --> 00:32:12,120 That's good. We've got some good clapping there. 605 00:32:12,120 --> 00:32:13,880 Some top clapping there. 606 00:32:15,480 --> 00:32:18,240 Yeah. OK. Now, I can't lie. 607 00:32:18,240 --> 00:32:19,920 I could still see all your hands moving. 608 00:32:19,920 --> 00:32:21,880 You weren't going as quickly as the vocal cords. 609 00:32:21,880 --> 00:32:23,080 Let's try it with your feet. 610 00:32:23,080 --> 00:32:25,120 How quickly can you tap your feet on the ground? 611 00:32:25,120 --> 00:32:27,160 Very good. That's very good. 612 00:32:27,160 --> 00:32:28,400 Very quick. 613 00:32:28,400 --> 00:32:31,320 I can still see your knees moving. 614 00:32:31,320 --> 00:32:32,920 You're not quite going that fast. 615 00:32:32,920 --> 00:32:35,200 So, let's try something else. 616 00:32:35,200 --> 00:32:36,960 Blow a raspberry at me, please. 617 00:32:42,800 --> 00:32:44,360 OK. Enough raspberries. 618 00:32:44,360 --> 00:32:46,240 Thank you. Thank you. 619 00:32:46,240 --> 00:32:48,400 Now, that was fast. 620 00:32:48,400 --> 00:32:50,520 And that's because, when you blow a raspberry, 621 00:32:50,520 --> 00:32:53,480 you do something very similar to how you make a sound at your larynx. 622 00:32:53,480 --> 00:32:58,360 Instead of moving your hands back and forth to clap or your feet up and down to tap, 623 00:32:58,360 --> 00:33:01,080 you don't move your lips up and down to blow a raspberry. 624 00:33:01,080 --> 00:33:03,440 You blow air through them. 625 00:33:03,440 --> 00:33:06,640 And that's exactly what happens when you are making a sound at your 626 00:33:06,640 --> 00:33:08,280 larynx. You blow air through. 627 00:33:08,280 --> 00:33:10,240 So, you're not moving the larynx back and forth. 628 00:33:10,240 --> 00:33:13,080 You're using your breath to control that. 629 00:33:13,080 --> 00:33:15,120 And, for this next demonstration, 630 00:33:15,120 --> 00:33:18,560 of exactly how that makes us make a sound in our larynx, 631 00:33:18,560 --> 00:33:21,960 I need two big balloons. 632 00:33:25,040 --> 00:33:26,080 And a volunteer. 633 00:33:27,280 --> 00:33:29,120 OK. Can I have you, please? 634 00:33:29,120 --> 00:33:32,600 Thank you very much. Fantastic! 635 00:33:32,600 --> 00:33:34,440 Thank you. Just ducking underneath this. 636 00:33:36,680 --> 00:33:38,880 Can you come and stand here for me, please? 637 00:33:40,520 --> 00:33:41,440 OK. 638 00:33:42,560 --> 00:33:47,320 Thank you. Now, this is extremely normal, as I'm sure you'll agree. 639 00:33:47,320 --> 00:33:49,040 What's your name? Isaac. 640 00:33:49,040 --> 00:33:52,560 Isaac. Now, what I'm going to ask you to do, Isaac, in just a second, 641 00:33:52,560 --> 00:33:56,320 is to take a leaf blower and we're going to blow some air between these 642 00:33:56,320 --> 00:33:59,720 two big balloons. People in the audience, I want you to think, 643 00:33:59,720 --> 00:34:03,040 when we blow a big blast of air through these balloons, 644 00:34:03,040 --> 00:34:06,440 is that going to push the balloons further apart or is it going to pull 645 00:34:06,440 --> 00:34:10,840 the balloons together? Put your hands up if you think it's going to blow them apart? 646 00:34:10,840 --> 00:34:14,320 Excellent. Put your hands up if you think it's going to pull them together. Very good. 647 00:34:14,320 --> 00:34:16,080 Very good. Slightly more for apart. 648 00:34:16,080 --> 00:34:18,320 In that case, what we're going to do is to test this. 649 00:34:18,320 --> 00:34:20,000 So, what I need you to do, Isaac, 650 00:34:20,000 --> 00:34:24,520 is to pop on some safety glasses and pop these on. 651 00:34:24,520 --> 00:34:27,680 OK. And now, for your lifelong ambition... 652 00:34:30,560 --> 00:34:32,880 ..an enormous leaf blower. I'm going to come this side. 653 00:34:32,880 --> 00:34:34,560 Now, I'm going to count you in. 654 00:34:34,560 --> 00:34:37,920 You turn it on there and kind of point it right through the middle. 655 00:34:37,920 --> 00:34:42,240 OK. Three, two, one...go. 656 00:34:42,240 --> 00:34:46,120 BLOWER WHIRS 657 00:34:46,120 --> 00:34:48,520 They're moving. They're moving together, aren't they? 658 00:34:48,520 --> 00:34:51,120 Keep going, keep going. And... 659 00:34:54,480 --> 00:34:58,760 OK. Fantastic! Turn off the blower, Isaac. Thank you. 660 00:35:01,000 --> 00:35:03,520 Now, don't go anywhere. 661 00:35:03,520 --> 00:35:06,760 So, if you thought they were going to get pulled together, you were right. 662 00:35:06,760 --> 00:35:08,520 It's very counterintuitive. 663 00:35:08,520 --> 00:35:12,360 But what happens when you blast the air through the middle of these two 664 00:35:12,360 --> 00:35:15,480 balloons is something called the Bernoulli principle. 665 00:35:15,480 --> 00:35:19,240 The Bernoulli principle says, when you have air that's moving more quickly, 666 00:35:19,240 --> 00:35:23,800 the air pressure within that air is lower than in the surrounding areas. 667 00:35:23,800 --> 00:35:27,720 What that does is it pulls the balloons together. 668 00:35:27,720 --> 00:35:29,360 Not pushing them further apart. 669 00:35:29,360 --> 00:35:32,600 They're pulled in. This is just like your shower curtain sticking to your 670 00:35:32,600 --> 00:35:35,440 leg when you're in the shower because the air has been moved round 671 00:35:35,440 --> 00:35:37,440 by the movement of the water. 672 00:35:37,440 --> 00:35:40,320 The other thing you'll notice, as we carried on - 673 00:35:40,320 --> 00:35:42,080 as Isaac carried on blowing - 674 00:35:42,080 --> 00:35:46,640 was that the balloons also then moved apart and then came back together, 675 00:35:46,640 --> 00:35:48,280 and they started to bounce. 676 00:35:48,280 --> 00:35:51,480 They're being pulled apart by things like gravity 677 00:35:51,480 --> 00:35:54,680 and the Bernoulli forces pulling back in again. 678 00:35:54,680 --> 00:35:58,040 That's exactly what happens in your larynx. 679 00:35:58,040 --> 00:36:01,320 You hold the larynx vocal folds together in the larynx. 680 00:36:01,320 --> 00:36:02,800 You blow air through them, 681 00:36:02,800 --> 00:36:06,640 and they're pushed apart and snap back together under these forces of 682 00:36:06,640 --> 00:36:09,560 elasticity and the Bernoulli principle. 683 00:36:09,560 --> 00:36:11,640 That's giving us those fast vibrations. 684 00:36:11,640 --> 00:36:12,600 Isaac, thank you. 685 00:36:17,080 --> 00:36:18,120 Thank you. 686 00:36:19,880 --> 00:36:20,880 But, is this... 687 00:36:22,400 --> 00:36:24,480 ..the full story of how we make sounds? 688 00:36:24,480 --> 00:36:27,440 We're making a noise at the larynx by blowing air through the vocal folds 689 00:36:27,440 --> 00:36:29,080 and causing them to vibrate. 690 00:36:30,120 --> 00:36:31,760 The vocal folds are amazing. 691 00:36:31,760 --> 00:36:34,440 They are an incredible piece of anatomy. 692 00:36:34,440 --> 00:36:37,440 They produce phenomenal ranges of sounds. 693 00:36:37,440 --> 00:36:42,160 And they're kind of rich with all sorts of different kinds of potential information. 694 00:36:42,160 --> 00:36:45,640 It's very, very important in terms of how we communicate with sound, 695 00:36:45,640 --> 00:36:47,480 but it's not the whole story. 696 00:36:49,000 --> 00:36:52,240 If we record the sound from the vocal folds and play it back, 697 00:36:52,240 --> 00:36:54,320 it sounds like this. 698 00:36:54,320 --> 00:36:58,560 MUFFLED SCRATCHING 699 00:37:01,040 --> 00:37:02,800 Anybody recognise that? 700 00:37:05,440 --> 00:37:08,560 It's Jack and Jill. So, it's a very over-familiar nursery rhyme 701 00:37:08,560 --> 00:37:11,800 which you can recognise because the sound at the vocal folds - 702 00:37:11,800 --> 00:37:14,200 it's got the right rhythm, it's got the right pitch. 703 00:37:14,200 --> 00:37:16,120 That's where you put that information in. 704 00:37:16,120 --> 00:37:20,160 But it didn't sound like a voice, it didn't sound like somebody talking. 705 00:37:20,160 --> 00:37:24,200 So, where does this other kind of information come in? 706 00:37:24,200 --> 00:37:27,240 Well, it turns out it's not enough to make vibrations. 707 00:37:27,240 --> 00:37:33,320 What you need to do is enhance, amplify, enrich those vibrations. 708 00:37:33,320 --> 00:37:37,200 And that comes down to another property of how sounds work. 709 00:37:37,200 --> 00:37:39,200 That's to do with resonance. 710 00:37:39,200 --> 00:37:41,160 If we can exploit resonance, 711 00:37:41,160 --> 00:37:45,480 we can make our communication with sound work much more efficiently. 712 00:37:45,480 --> 00:37:47,280 So, what's resonance? 713 00:37:47,280 --> 00:37:51,720 Resonance is just a characteristic of objects, things in the world, 714 00:37:51,720 --> 00:37:55,240 from molecules up to mountains - things, objects, 715 00:37:55,240 --> 00:37:58,360 have a frequency at which they will maximally vibrate. 716 00:37:58,360 --> 00:38:01,720 And we can use this property when we're making communication sounds to 717 00:38:01,720 --> 00:38:06,000 help maximise the sound vibrations that we're producing and therefore 718 00:38:06,000 --> 00:38:08,640 enhance their communicative properties. 719 00:38:08,640 --> 00:38:12,480 I'm going to show you how this works with an extremely simple demo. 720 00:38:15,800 --> 00:38:19,560 So, you can think of everything as having a rate at which it moves 721 00:38:19,560 --> 00:38:22,680 most efficiently, at which it will vibrate maximally. 722 00:38:22,680 --> 00:38:26,040 And here, we're seeing how that can be affected by the shapes of objects. 723 00:38:26,040 --> 00:38:28,320 Here, we've just got, as our objects, 724 00:38:28,320 --> 00:38:31,400 we've got four lovely Christmas baubles and, 725 00:38:31,400 --> 00:38:33,240 for the purpose of this demonstration, 726 00:38:33,240 --> 00:38:36,240 I want you to think of the whole thing - the bauble and the string - 727 00:38:36,240 --> 00:38:38,000 as being the shape of the object. 728 00:38:38,000 --> 00:38:42,160 What I'm going to do is move this ball here. 729 00:38:42,160 --> 00:38:46,200 What I want you to do is watch what happens to these guys. 730 00:38:52,960 --> 00:38:57,200 Now, you should notice that one of these Christmas baubles 731 00:38:57,200 --> 00:39:00,760 starts to move at a more exaggerated rate than the other ones. 732 00:39:00,760 --> 00:39:03,480 Can anyone call out the colour - the one that's moving the most? 733 00:39:03,480 --> 00:39:05,320 ALL: Red. It's red, exactly. 734 00:39:05,320 --> 00:39:07,440 Now, what does red have in common with this one? 735 00:39:07,440 --> 00:39:09,560 It's the same length. So, the shape... 736 00:39:09,560 --> 00:39:12,720 The overall shape of the whole thing is most similar across those two. 737 00:39:12,720 --> 00:39:14,680 And it's meaning, when I move this one, 738 00:39:14,680 --> 00:39:18,040 it's putting in the right kind of movement to vibrate something of a 739 00:39:18,040 --> 00:39:20,960 similar shape. So, if I change the shape of this guy... 740 00:39:23,240 --> 00:39:24,600 ..by shortening the string... 741 00:39:28,640 --> 00:39:30,720 ..and then do exactly the same thing. 742 00:39:30,720 --> 00:39:32,600 I'm just going to set this one moving. 743 00:39:36,600 --> 00:39:39,480 So now you can see, with this different shape, 744 00:39:39,480 --> 00:39:41,680 a different Christmas bauble is moving maximally... 745 00:39:43,160 --> 00:39:45,080 ..and what's happening here 746 00:39:45,080 --> 00:39:47,960 is I'm putting the kind of force in at the right 747 00:39:47,960 --> 00:39:49,840 kind of speed to cause 748 00:39:49,840 --> 00:39:53,960 maximal vibration with this Christmas bauble. 749 00:39:53,960 --> 00:39:56,280 And of course we do this all the time. 750 00:39:56,280 --> 00:40:00,240 We have a very intuitive understanding of how we can put 751 00:40:00,240 --> 00:40:03,600 the right kind of force into things that we want to move. 752 00:40:03,600 --> 00:40:06,200 If you ride on a swing, you know how to push that 753 00:40:06,200 --> 00:40:08,760 at the right kind of speed and the right kind of 754 00:40:08,760 --> 00:40:10,800 force to make yourself swing. 755 00:40:10,800 --> 00:40:13,240 And you do the same thing when you use your voice. 756 00:40:13,240 --> 00:40:15,160 When you make a sound with your voice, 757 00:40:15,160 --> 00:40:19,000 you're actually exploiting that kind of pressure of your air to get the 758 00:40:19,000 --> 00:40:22,400 right kind of resonance properties for the vibrations that you make. 759 00:40:22,400 --> 00:40:24,920 Sounds are made by vibrations 760 00:40:24,920 --> 00:40:28,920 and those vibrations are made bigger when the objects we make vibrate 761 00:40:28,920 --> 00:40:31,280 can hit their resonance frequency. 762 00:40:31,280 --> 00:40:34,040 This, amongst other things, can mean the sounds can be louder. 763 00:40:35,240 --> 00:40:37,960 Now we can see a more dramatic demonstration of this if we take a 764 00:40:37,960 --> 00:40:41,920 more complex object and explore its resonance characteristics. 765 00:40:41,920 --> 00:40:46,920 What we're going to try and do is find and exploit the resonance frequency of a wineglass. 766 00:40:49,000 --> 00:40:52,320 Now, when you make a wineglass make a sound like this, 767 00:40:52,320 --> 00:40:55,400 what you're doing is you're finding the resonance frequency. 768 00:40:55,400 --> 00:40:58,240 HUMMING 769 00:41:02,520 --> 00:41:06,320 So, I'm putting in the right kind of force at the right kind of speed to 770 00:41:06,320 --> 00:41:09,320 start resonating this glass and we can hear that. 771 00:41:09,320 --> 00:41:14,040 However, if we record that sound and play that sound back into the glass, 772 00:41:14,040 --> 00:41:18,280 we can see much more dramatic effects of that vibration. 773 00:41:18,280 --> 00:41:23,280 At this stage, I just need to ask everybody to put their earplugs in. 774 00:41:23,280 --> 00:41:26,680 You guys put your ear plugs in, and your safety glasses. 775 00:41:29,240 --> 00:41:32,760 So, what Fran has done earlier is she's calculated the resonance frequency 776 00:41:32,760 --> 00:41:37,160 of this wineglass and she's going to generate the right sound and 777 00:41:37,160 --> 00:41:41,400 put it through under great levels of intensity out of this loud speaker. 778 00:41:41,400 --> 00:41:44,320 And we'll start to see what that does to the wineglass. 779 00:41:44,320 --> 00:41:47,680 And we can see this because we've got the high-speed camera again. 780 00:41:47,680 --> 00:41:50,760 So, we need more light for that and you'll see that appearing on the 781 00:41:50,760 --> 00:41:53,440 screen. OK. Has everybody got their ears covered up? 782 00:41:54,480 --> 00:41:55,920 Off we go. 783 00:41:55,920 --> 00:41:59,560 HUMMING 784 00:42:01,720 --> 00:42:04,080 HUMMING AMPLIFIES 785 00:42:05,680 --> 00:42:07,120 There we go. 786 00:42:11,240 --> 00:42:12,280 That's amazing. 787 00:42:16,120 --> 00:42:17,600 If I leap over the debris, 788 00:42:17,600 --> 00:42:23,360 can you see how much that wineglass is moving before it breaks? 789 00:42:23,360 --> 00:42:26,600 How much those vibrations are causing it to distort and shake. 790 00:42:28,920 --> 00:42:30,440 Just when you think it can't 791 00:42:30,440 --> 00:42:32,560 possibly tolerate that much movement, 792 00:42:32,560 --> 00:42:34,720 it stops tolerating that much movement 793 00:42:34,720 --> 00:42:37,840 and we see the whole thing break to pieces. 794 00:42:41,240 --> 00:42:42,200 Whoa! 795 00:42:45,160 --> 00:42:47,280 That's the power of resonance. 796 00:42:49,320 --> 00:42:51,600 If you want to send your message further, 797 00:42:51,600 --> 00:42:54,600 resonance can really help you. 798 00:42:54,600 --> 00:42:58,280 But how are we exploiting resonance in our own bodies? 799 00:42:58,280 --> 00:42:59,560 I mean, to be brutally honest, 800 00:42:59,560 --> 00:43:02,920 we're not exploding wineglasses or anything dramatic like that. 801 00:43:02,920 --> 00:43:07,440 Actually, we're doing something a bit more like a musical instrument. 802 00:43:07,440 --> 00:43:09,440 I've got an example of a musical instrument here. 803 00:43:09,440 --> 00:43:10,880 Thank you very much, Natasha. 804 00:43:10,880 --> 00:43:12,920 So, we've got the basics of a musical instrument. 805 00:43:12,920 --> 00:43:15,760 We've got a string. I'm going to make that string vibrate 806 00:43:15,760 --> 00:43:17,160 by plucking it. 807 00:43:17,160 --> 00:43:19,840 DULL THUMP 808 00:43:19,840 --> 00:43:22,200 Now you can kind of hear something, can't you? 809 00:43:22,200 --> 00:43:23,680 You can see something's moving. 810 00:43:23,680 --> 00:43:25,120 There's not very much sound there. 811 00:43:28,120 --> 00:43:31,800 What we can do is make that much more impressive 812 00:43:31,800 --> 00:43:34,200 by bringing in a bit more resonance. 813 00:43:38,120 --> 00:43:39,320 Thank you. 814 00:43:39,320 --> 00:43:41,640 So, this is just a tea chest. 815 00:43:41,640 --> 00:43:42,840 It's an empty tea chest. 816 00:43:42,840 --> 00:43:44,720 Well, it's not empty. It's filled with air. 817 00:43:44,720 --> 00:43:47,600 What we're going to do is use the resonance properties 818 00:43:47,600 --> 00:43:51,680 of the tea chest and the air inside it to really exploit the vibrations 819 00:43:51,680 --> 00:43:53,720 that we're making with the exact same string, 820 00:43:53,720 --> 00:43:57,680 and the exact same stick that you just saw before. 821 00:43:57,680 --> 00:43:59,560 If we do that, you can hear a sound. 822 00:43:59,560 --> 00:44:02,680 LOW-PITCHED NOTE A much louder sound. 823 00:44:02,680 --> 00:44:05,560 LOW-PITCHED NOTE 824 00:44:05,560 --> 00:44:09,440 Where's that sound actually coming from? Are we hearing the sound of string? 825 00:44:09,440 --> 00:44:10,720 We're probably not. 826 00:44:10,720 --> 00:44:14,320 We can actually image that with this fantastic device here. 827 00:44:14,320 --> 00:44:16,720 This is actually an acoustic camera. 828 00:44:16,720 --> 00:44:19,560 It's really a rather beautiful array of microphones. 829 00:44:19,560 --> 00:44:22,560 It looks like a spectacular tree. 830 00:44:22,560 --> 00:44:28,280 What that's going to be used for is to give a spatial location to where 831 00:44:28,280 --> 00:44:29,920 sounds are coming from. 832 00:44:29,920 --> 00:44:32,040 So, if I make a sound... 833 00:44:32,040 --> 00:44:38,400 Tch! 834 00:44:38,400 --> 00:44:41,680 You can see that the sound source is coming from the front of my face, 835 00:44:41,680 --> 00:44:44,080 which is correct. That's how I was making that sound. 836 00:44:44,080 --> 00:44:47,000 Now if we try this with our bass 837 00:44:47,000 --> 00:44:49,560 and see if we can see that making a sound. 838 00:44:49,560 --> 00:44:52,120 LOW-PITCHED NOTE 839 00:44:52,120 --> 00:44:55,360 It's the air, the vibrating air, that's causing the sound. 840 00:44:55,360 --> 00:44:57,440 It's coming out from the bottom of the bass. 841 00:44:57,440 --> 00:45:01,240 STRUMMING 842 00:45:11,520 --> 00:45:13,960 There we go. Thank you very much, acoustic camera. 843 00:45:18,480 --> 00:45:23,080 So, a simple demonstration of how adding in the resonance here 844 00:45:23,080 --> 00:45:26,760 of some air inside the box helps us hear the vibration of that string 845 00:45:26,760 --> 00:45:30,240 completely differently. And we're doing something very similar. 846 00:45:30,240 --> 00:45:32,800 We're taking the resonance characteristics 847 00:45:32,800 --> 00:45:34,280 of our own vocal tract, 848 00:45:34,280 --> 00:45:36,760 and we're using that to shape and enrich 849 00:45:36,760 --> 00:45:38,960 the sound we make at our larynx. 850 00:45:38,960 --> 00:45:41,920 So, if we look here at my cutaway head. 851 00:45:41,920 --> 00:45:46,120 This is just showing you the shape of the air tubes we're sending sound 852 00:45:46,120 --> 00:45:48,720 into when we make a sound at our larynx. 853 00:45:48,720 --> 00:45:50,520 The larynx is sitting down here. 854 00:45:52,000 --> 00:45:53,880 It's sitting down actually in the windpipe - 855 00:45:53,880 --> 00:45:55,320 it's quite low down in humans, 856 00:45:55,320 --> 00:45:57,840 much lower down than it is in other primates. 857 00:45:57,840 --> 00:46:02,560 What that gives us is a much longer tube for making the sounds that we 858 00:46:02,560 --> 00:46:06,160 make with our voices. It's a long way from our larynx to our lips. 859 00:46:06,160 --> 00:46:09,080 That's called our vocal tract. It's actually made of two tubes. 860 00:46:09,080 --> 00:46:11,040 We've got one tube coming up through our mouth, 861 00:46:11,040 --> 00:46:13,160 one coming up through our nose. 862 00:46:13,160 --> 00:46:15,320 There are two aspects to this. 863 00:46:15,320 --> 00:46:19,200 Our lowered larynx gives us a longer tube to make the sounds with. 864 00:46:19,200 --> 00:46:21,480 It's giving us a richer sound. 865 00:46:21,480 --> 00:46:23,400 And also, what we can do 866 00:46:23,400 --> 00:46:26,480 is we can modify the shape of our mouths 867 00:46:26,480 --> 00:46:29,200 and change the resonance characteristics. 868 00:46:29,200 --> 00:46:32,280 So, if you all go... Eee! 869 00:46:32,280 --> 00:46:34,600 ALL: Eee! 870 00:46:34,600 --> 00:46:37,000 Ooh! Ooh! 871 00:46:37,000 --> 00:46:40,000 Now, that's you changing the resonance characteristics of your 872 00:46:40,000 --> 00:46:42,720 own vocal tract and it's giving you a different sound. 873 00:46:42,720 --> 00:46:45,680 So, we have a richer sound, we have a more complex sound. 874 00:46:45,680 --> 00:46:48,080 It's as if we have a musical instrument where we could change 875 00:46:48,080 --> 00:46:49,600 the shape of it all the time. 876 00:46:49,600 --> 00:46:52,760 And we use that really importantly for how we communicate 877 00:46:52,760 --> 00:46:55,520 with sound. Our lowered larynxes are giving us 878 00:46:55,520 --> 00:46:58,000 this richer range of sound. 879 00:46:58,000 --> 00:47:03,240 In adult men, we see another movement down of the larynx. 880 00:47:03,240 --> 00:47:05,600 In adolescents, boys' voices break. 881 00:47:05,600 --> 00:47:08,640 What that literally means is the larynx moves physically further down. 882 00:47:08,640 --> 00:47:12,200 And you can see an Adam's apple in the neck of most men. 883 00:47:12,200 --> 00:47:15,400 This gives men an even longer tube 884 00:47:15,400 --> 00:47:18,360 to make the sounds of speech in their voice with and it gives them 885 00:47:18,360 --> 00:47:21,120 a deeper, richer-sounding voice. 886 00:47:21,120 --> 00:47:26,000 But, it turns out, humans are not the only animals that have a larynx 887 00:47:26,000 --> 00:47:27,840 which we can manoeuvre in this way. 888 00:47:29,520 --> 00:47:33,640 Fallow deer - male fallow deer - compete to mate with females. 889 00:47:33,640 --> 00:47:36,440 Professor David Reby from the University of Sussex 890 00:47:36,440 --> 00:47:40,400 went to look at how the bucks use their voices to communicate their 891 00:47:40,400 --> 00:47:43,680 size and try and impress those females and each other. 892 00:47:47,120 --> 00:47:49,160 Hello, Sophie. Hi, everyone. 893 00:47:49,160 --> 00:47:50,760 So, today, we're in Petworth Park. 894 00:47:50,760 --> 00:47:55,040 This time of the year, the fallow deer engage in what we call the rut. 895 00:47:55,040 --> 00:48:00,120 During the rut, the males produce a very large number of vocalisations, 896 00:48:00,120 --> 00:48:02,240 called groans. DEER GROANS 897 00:48:02,240 --> 00:48:04,440 And these groans are very low pitch. 898 00:48:04,440 --> 00:48:08,400 And we believe that they produce this vocalisation in order 899 00:48:08,400 --> 00:48:11,000 to communicate information about the body size. 900 00:48:19,440 --> 00:48:22,640 We're going to play back groans which have been resynthesized, 901 00:48:22,640 --> 00:48:24,840 where I've either lowered the resonances, 902 00:48:24,840 --> 00:48:28,720 so that the buck sounds a lot larger than it actually is, 903 00:48:28,720 --> 00:48:31,800 or where I've raised the resonances, to make it sound a lot smaller. 904 00:48:34,120 --> 00:48:37,480 So, what I'm going to do now is to play the small version. 905 00:48:37,480 --> 00:48:41,560 LOW-PITCHED GROANS 906 00:48:42,520 --> 00:48:45,600 Clearly puzzled by the playback. 907 00:48:47,680 --> 00:48:51,440 I'm going to play back a very large buck. Look at this guy. 908 00:48:51,440 --> 00:48:54,040 DEEPER-PITCHED GROAN 909 00:48:54,040 --> 00:48:57,640 We've definitely got their attention here. 910 00:48:57,640 --> 00:49:00,720 You can see he's clearly intimidated. 911 00:49:00,720 --> 00:49:04,160 I think you could really see the response of the buck to the first 912 00:49:04,160 --> 00:49:07,960 sequence, where the caller sounds smaller. 913 00:49:07,960 --> 00:49:11,640 We had quite a timid reaction from the target animal, 914 00:49:11,640 --> 00:49:15,920 whereas when we played the groans where the resonance had been lowered 915 00:49:15,920 --> 00:49:20,000 to make the animal sound a lot larger, we get a much 916 00:49:20,000 --> 00:49:24,160 stronger response from the target buck. 917 00:49:30,400 --> 00:49:33,480 David was actually the first scientist to realise that deer 918 00:49:33,480 --> 00:49:35,840 were able to do this with their voices 919 00:49:35,840 --> 00:49:39,400 and he's been taking Cat scans of deer vocal tracts. 920 00:49:39,400 --> 00:49:42,760 You can see that here. So, that's the length of the neck. 921 00:49:42,760 --> 00:49:47,880 It's giving you some idea of how far they can move their larynx up and down. 922 00:49:47,880 --> 00:49:50,840 We think we've got fairly impressive vocal tracts. 923 00:49:50,840 --> 00:49:52,720 Deer are much, much larger 924 00:49:52,720 --> 00:49:54,880 and they're moving their larynx really a long 925 00:49:54,880 --> 00:49:58,320 way up and down to create this incredible range of sounds. 926 00:49:58,320 --> 00:50:02,440 The deeper voice, maybe it suggests power and strength. 927 00:50:02,440 --> 00:50:05,080 Maybe this has some similar role in humans. 928 00:50:05,080 --> 00:50:08,320 Maybe this secondary descent of the larynx that boys go through in 929 00:50:08,320 --> 00:50:12,160 adolescence is adding in aspects of their voice which are potentially 930 00:50:12,160 --> 00:50:14,920 conveying dominance or size. 931 00:50:14,920 --> 00:50:19,000 It's certainly possibly giving men the sound of a bigger body without 932 00:50:19,000 --> 00:50:22,760 actually having to grow a larger and more expensive bigger body. 933 00:50:22,760 --> 00:50:25,280 We're seeing sounds generally, however, 934 00:50:25,280 --> 00:50:28,480 as being something we can think of as actions. 935 00:50:28,480 --> 00:50:32,240 All sounds happen because something happened in the world and the things 936 00:50:32,240 --> 00:50:36,120 that interacted to cause those sounds to happen also affect the sound. 937 00:50:36,120 --> 00:50:40,000 As the bodies get bigger, the sounds gets deeper and they get richer. 938 00:50:41,880 --> 00:50:44,840 We've seen a variety of different ways that animals can communicate 939 00:50:44,840 --> 00:50:48,160 and they're orchestrating this physics of vibration and resonance 940 00:50:48,160 --> 00:50:51,520 to help communicate with each other, to send and receive messages. 941 00:50:51,520 --> 00:50:54,400 And, of course, the more you can vary these sound waves, 942 00:50:54,400 --> 00:50:57,480 the more complex the messages you can communicate. 943 00:50:58,520 --> 00:51:04,520 Now, humans are exceptionally good at really rapidly and precisely 944 00:51:04,520 --> 00:51:07,560 modifying the sound we make when we use our voices. 945 00:51:07,560 --> 00:51:11,080 We can shape and interrupt the flow of air with our tongues, our lips, 946 00:51:11,080 --> 00:51:13,440 our teeth, our jaw and, of course, 947 00:51:13,440 --> 00:51:16,720 this is one of the main ingredients for one of our most important sound 948 00:51:16,720 --> 00:51:19,200 communications...speech. 949 00:51:19,200 --> 00:51:21,120 To show exactly how we do this, 950 00:51:21,120 --> 00:51:24,160 please welcome my friend and colleague, Reeps. 951 00:51:26,880 --> 00:51:28,520 Hi. Thank you. 952 00:51:35,000 --> 00:51:38,400 Now, Reeps, can you start by taking us through some plosive sounds? 953 00:51:38,400 --> 00:51:42,560 Plosive sounds are where we make a closure with our lips and then spit 954 00:51:42,560 --> 00:51:44,600 the sound out. Yes, of course. 955 00:51:44,600 --> 00:51:49,680 HE BEATBOXES 956 00:52:05,400 --> 00:52:08,560 Now, I've worked in speech for many years and I always used to start all 957 00:52:08,560 --> 00:52:12,880 my talks by saying human speech is the most complex sound in nature and 958 00:52:12,880 --> 00:52:16,040 then I met Reeps, and I realised, because you'll have just spotted, 959 00:52:16,040 --> 00:52:19,080 he was beatboxing. He's one of the world's greatest beatboxers. 960 00:52:19,080 --> 00:52:21,720 He does this incredible, amazing noise. 961 00:52:21,720 --> 00:52:25,000 It's the speed at which he's doing things, the sounds he's producing. 962 00:52:25,000 --> 00:52:27,200 It so much more than we do when we're talking. 963 00:52:27,200 --> 00:52:29,720 We can actually look at that in a bit more detail. 964 00:52:29,720 --> 00:52:32,160 Are you OK to come and stand over here? Yes. Of course. 965 00:52:32,160 --> 00:52:35,520 What we've done is we've put Reeps into our MRI machine 966 00:52:35,520 --> 00:52:39,320 and we've run that like a video camera, so we can actually image 967 00:52:39,320 --> 00:52:43,200 his vocal tract and how he's changing it while he beatboxes 968 00:52:43,200 --> 00:52:45,840 and you can see that on the monitor here. 969 00:52:45,840 --> 00:52:50,800 HE BEATBOXES 970 00:53:10,320 --> 00:53:12,000 Thank you. Brilliant. Thank you. 971 00:53:18,760 --> 00:53:20,280 That's absolutely extraordinary. 972 00:53:20,280 --> 00:53:23,280 You could hear at certain points how he was producing at least two 973 00:53:23,280 --> 00:53:24,560 different sounds at once. 974 00:53:24,560 --> 00:53:26,960 And that's not technically supposed to be possible. 975 00:53:26,960 --> 00:53:28,320 Apparently no-one told you. 976 00:53:29,640 --> 00:53:32,400 Is it the case that this is just a learnable skill? 977 00:53:32,400 --> 00:53:34,520 Did you teach yourself this? 978 00:53:34,520 --> 00:53:37,560 I started because I played lots of instruments when I was younger. 979 00:53:37,560 --> 00:53:41,000 I wanted to make music all the time and it's a way to internalise music 980 00:53:41,000 --> 00:53:44,440 very quickly. And I completely taught myself. 981 00:53:44,440 --> 00:53:47,160 Listening to music, listening to things that are out there, 982 00:53:47,160 --> 00:53:50,040 it's possible for people to create their own music 983 00:53:50,040 --> 00:53:53,600 with themselves all the time. And could any of us learn to do this? 984 00:53:53,600 --> 00:53:57,400 Absolutely. Every single person in this room can start exploring sounds. 985 00:53:57,400 --> 00:53:59,600 We all use 26 sounds in the alphabet. 986 00:53:59,600 --> 00:54:01,960 Three of those sounds - puh, tuh and kuh - 987 00:54:01,960 --> 00:54:05,800 can easily become music and you're all welcome to explore. 988 00:54:05,800 --> 00:54:08,280 Excellent. Thank you very much, Reeps. My pleasure. 989 00:54:08,280 --> 00:54:11,040 If you wouldn't mind just sitting there. Don't go anywhere. 990 00:54:18,560 --> 00:54:22,520 So, one thing that's really striking is that human vocal abilities, 991 00:54:22,520 --> 00:54:25,720 if anything, are over-engineered for speech. 992 00:54:25,720 --> 00:54:28,880 I thought speech was so complex and then I saw things like beatboxing 993 00:54:28,880 --> 00:54:31,560 and I realise we're actually doing almost the bare minimum 994 00:54:31,560 --> 00:54:33,680 when we talk to each other. 995 00:54:33,680 --> 00:54:37,080 So, I wonder if there might be some other aspect of our communication 996 00:54:37,080 --> 00:54:40,160 and our voices that might have driven our evolution of this 997 00:54:40,160 --> 00:54:43,160 really extraordinary musical instrument that we have. 998 00:54:43,160 --> 00:54:46,440 So, please, can I introduce my last guest, Katherine Woodward? 999 00:54:57,160 --> 00:55:00,800 Now, I've made a movie of you in our scanner, 1000 00:55:00,800 --> 00:55:02,560 looking at your vocal tract. 1001 00:55:02,560 --> 00:55:04,480 Yes. Can I position you here? 1002 00:55:04,480 --> 00:55:05,960 Can you sing along to that for us? 1003 00:55:05,960 --> 00:55:07,720 Is that OK? Thank you very much. 1004 00:55:10,080 --> 00:55:13,600 SHE SINGS OPERA 1005 00:55:36,840 --> 00:55:41,480 Lovely. Thank you. 1006 00:55:42,800 --> 00:55:44,520 You can see in Katherine's voice, 1007 00:55:44,520 --> 00:55:47,320 the range and the shape she's creating in her vocal tract 1008 00:55:47,320 --> 00:55:52,160 to produce a sound of such power, such strength, such thrillingness. 1009 00:55:52,160 --> 00:55:55,480 And, of course, we can all potentially learn to do this. 1010 00:55:55,480 --> 00:55:57,680 We might never be as good as Katherine, 1011 00:55:57,680 --> 00:55:59,440 but it's a learnable skill. 1012 00:55:59,440 --> 00:56:00,840 We all learn to speak. 1013 00:56:00,840 --> 00:56:04,200 We can all learn these other kinds of vocal abilities. 1014 00:56:04,200 --> 00:56:07,840 And one theory does suggest that what we might be looking at, 1015 00:56:07,840 --> 00:56:10,920 because we can do so much more than we do when we're normally talking to 1016 00:56:10,920 --> 00:56:14,840 each other, we might have evolved this ability for vocal gymnastics 1017 00:56:14,840 --> 00:56:17,320 before we were ever using it for speaking. 1018 00:56:17,320 --> 00:56:21,040 Possibly, our vocal range and complexity may have been a way for 1019 00:56:21,040 --> 00:56:24,320 our ancestors to win mates, or defend territories, 1020 00:56:24,320 --> 00:56:27,760 much in the same way as we see birds nowadays using sounds to impress 1021 00:56:27,760 --> 00:56:32,800 other birds. Once we'd evolved this absolutely extraordinary musical 1022 00:56:32,800 --> 00:56:37,040 instrument of the human voice, maybe speech was almost an invention, 1023 00:56:37,040 --> 00:56:39,640 an afterthought. It's an afterthought, of course, 1024 00:56:39,640 --> 00:56:42,360 that's created the world we live in, through the gift of language. 1025 00:56:44,480 --> 00:56:48,440 Whether you are a cricket, or cockroach, a deer or an elephant, 1026 00:56:48,440 --> 00:56:52,120 the ability to communicate with sounds can be absolutely critical to 1027 00:56:52,120 --> 00:56:55,920 your survival. Thinking about the human voice as an instrument for 1028 00:56:55,920 --> 00:57:00,440 social, emotional, as well as spoken communication can help us understand possibly 1029 00:57:00,440 --> 00:57:03,960 why we ever evolved such an extraordinary musical instrument 1030 00:57:03,960 --> 00:57:06,120 of such complexity and range. 1031 00:57:06,120 --> 00:57:10,480 So, for our finale, I would like to invite you, and our guests, 1032 00:57:10,480 --> 00:57:12,280 both animal and human, 1033 00:57:12,280 --> 00:57:16,240 to really try and show the full extent of what our voices can do. 1034 00:57:16,240 --> 00:57:18,760 Harry, Katherine, if I can have you back. 1035 00:57:18,760 --> 00:57:22,680 And let me introduce Steven, who is our composer for this evening. 1036 00:57:36,680 --> 00:57:39,360 3, 2, 1... 1037 00:57:39,360 --> 00:57:43,320 TUNING FORK DINGS, BUZZING, HISSING, GRUNTS, ELEPHANT TRUMPETS 1038 00:57:46,760 --> 00:57:51,520 HE BEATBOXES WHILE PREVIOUS SOUNDS CONTINUE 1039 00:57:54,440 --> 00:57:58,120 SHE STRUMS WHILE PREVIOUS SOUNDS CONTINUE 1040 00:58:01,920 --> 00:58:07,920 ALL SING "AH" WHILE PREVIOUS SOUNDS CONTINUE