Human Senses - S1.E5 ∙ Hearing
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00:00The
00:25sounds we hear can have amazing effects on us.
00:36Change the music and these menacing killer sharks are transformed into beautiful wonders
00:42of nature.
00:56So which are they?
01:01These are Caribbean reef sharks and even though they may nip me, that's why I've got this
01:06shark-proof suit on, they certainly aren't man-eaters.
01:11Look at that.
01:13Without the scary soundtrack, the sharks don't seem as menacing.
01:18That's the power of sound.
01:20I'm going to discover how our sense of hearing can really have an incredible effect on how
01:26we experience the world around us.
01:51Tonight we're going to explore the astonishingly powerful effects that what we hear can have
01:57on us.
01:58From this, and this, to this.
02:06I'm Nigel Marvin and I've spent my whole life studying animals and I'll be trying to find
02:11out why we're so moved by the sound of music by listening in to humpback whales.
02:19Did you see that breach?
02:21I'll discover how what we hear can turn us on, or make us weep, before finally discovering
02:34why something as loud as this can make you feel like this.
02:48We live in a world of constant noise.
03:04Most of it just washes over us, but some sounds cut right through the din and affect us deeply.
03:16In my quest for sounds which have the most profound effect on us, where better to start
03:21than with the ones that hit a raw nerve?
03:26Some sounds are just so unbearable they can reduce any of us, however tough, to quivering
03:32jelly.
03:37I'm not talking about everyday noise pollution, those loud incessant sounds that do your head
03:42in.
03:47I'm not even talking about harsh sounds that can be hard to ignore.
03:53Baby's wailing.
04:01Some people find soft noises even more unpleasant than that.
04:10Car alarms, yep, they f**k you up, car alarms.
04:14Oh that's obnoxious, absolutely obnoxious.
04:21Oh I hate that, oh, I'm going to shoot them.
04:24All very unpleasant, but in surveys of the noises people hate most, there's one sound
04:30which beats all these.
04:32You might want to turn the volume down for this one.
04:35Even the thought of it is deeply unpleasant.
04:37No!
04:38That's nasty actually.
04:41Are you ready?
04:44You're about to hear the world's most annoying sound.
04:48Terrible, don't say that.
04:52Oh no, don't.
04:55What a noise, it is horrendous.
05:00The sound of fingers on a blackboard is almost unbearable.
05:09That a noise can have such an astonishingly powerful effect on us is quite extraordinary
05:14when you stop to think about what sound consists of.
05:24Sounds are just tiny movements of the air molecules around us, but our ears contain
05:29a wonderful system for detecting these faint ripples in the air.
05:39First the sound waves are funnelled down the ear canal to the eardrum.
05:44If they were slowed down massively, this is what they'd look like.
05:48The moving air makes the eardrum vibrate.
05:51These vibrations are then amplified by three hinged bones.
05:55The bones are connected to a curled tube called the cochlea, which is full of fluid.
06:01The vibrations of the bones send ripples through the fluid, and these ripples move rows of
06:06microscopic hair cells.
06:09As the hair cells are bent, they send nerve signals to the brain, which then works out
06:13what the sound is.
06:15It's an extraordinary contraption, but it works beautifully.
06:29The human ear is a marvel of natural engineering, capable of detecting sounds that are so quiet
06:35that they cause our eardrums to vibrate less than the width of an atom.
06:45Yet our ears can cope with sounds that are billions of times louder, without damaging
06:50our hearing.
07:12And with our two ears, we can even tell where a sound is coming from.
07:16Our brains pinpoint the source by comparing the precise moment the sound reaches each
07:22ear.
07:23And all this is achieved with something as tiny as this, the moving bones inside our
07:29ears.
07:31We're equipped with a fantastic system for hearing a phenomenal range of sounds.
07:39But out of all the noises we hear, why do we respond so strongly to a few particular
07:44kinds of sound?
07:52I've come to Florida with wildlife expert Tim Williams to meet a prehistoric creature.
08:03My old friend, the alligator.
08:12Alligators were around before the dinosaurs, and they can tell us something about the origins
08:17of our own sense of hearing.
08:20Amazingly, all modern reptiles, birds and mammals, including us, have ears based on
08:26the same ancient design.
08:29Look, on the side of the head, just behind the eye, there's their ear.
08:37If I look closely, they've got an ear just like ours.
08:43I can see the eardrum, and it goes right inside to the inner ear.
08:53Once you live on land, being able to hear sounds travelling through the air is crucial
08:58for survival.
09:01It helps parents keep track of their young.
09:07It's also a good way to communicate, to warn off rivals, and most importantly, to serenade
09:18a mate.
09:21In the breeding season, the male alligators try to impress the females with deep bellowing.
09:27Almost any low-frequency rumble will get them going.
09:30Hey, Jason, fire up the airboat.
09:3410-4.
09:35Look at the water dancing off the back, just like diamonds in the sunlight.
09:54Across the animal kingdom, sounds can have powerful effects on members of the opposite
09:59sex, and we're just the same.
10:03For us humans, the sound of another human voice can be a real turn-on.
10:07At the third beep, it will be ten past twelve.
10:21Behavioural expert Sarah Collins has been studying how the sound of some voices can
10:26work wonders.
10:27On the third beep, it will be ten past twelve.
10:29At the third beep, it will be ten past twelve.
10:30At the third beep, it will be ten past twelve.
10:34So in a few seconds, you're going to hear a male voice.
10:38While he's speaking, I want you to think about it carefully, and afterwards I'll ask you
10:41a few questions about what you think of that voice.
10:46At the third beep, it will be ten past twelve.
10:50It's a rich, deep voice, yes, attractive voice.
10:54At the third beep, it will be ten past twelve.
10:58Sounds like quite an attractive voice, it's quite deep.
11:00At the third beep, it will be ten past twelve.
11:05It's hardly love poetry, but his voice alone is conjuring up vivid images.
11:11Probably quite a large body build.
11:13Dark hair, thick hair.
11:15Probably tall and big hands.
11:20Sarah Collins has found that most women imagine that men with rich, deep voices are more muscular,
11:26attractive and even have hairier chests than their higher-voiced counterparts.
11:32If a man has a deeper voice, the kind of assumptions women make about that man tend to be that
11:39he's slightly more dominant, that he is somehow more masculine, more likely to have bristles,
11:44is more likely to be big and beefy.
11:46At the third beep, it will be ten past twelve.
11:49A bit sexy.
11:52And the effect seems to work the other way too.
11:55A husky female voice can really get a man's imagination going.
12:00At the third beep, it will be ten past twelve.
12:03So, what did you think of that voice then?
12:06I thought it was quite an attractive voice.
12:07I think it sounds pretty sexy actually, yeah.
12:11I think she'd be quite curvy.
12:13Not too tall, but just felt right.
12:17Associated with maybe being quite frisky.
12:23Well, I think the reason that men find husky voices attractive is simply because
12:26if somebody's sexually aroused, then their voices get more husky.
12:30So, huskiness just makes you think of somebody being sexually aroused.
12:36But voices can be deceptive.
12:38Most of us are actually surprisingly bad at predicting what people will look like
12:43from the sound of their voice.
12:46Annoying noises we can't stand or warm, inviting voices.
12:50Sounds that get to us.
12:52But sometimes things we hear can cut through even when we're totally unconscious.
12:58There are times when a good sense of hearing can be a matter of life and death.
13:04In the day, our monkey ancestors used their eyes to detect predators.
13:13But at night, they relied on their ears.
13:29And every night, when all our other senses have shut down,
13:32our hearing is still on the alert for danger.
13:44At his sleep laboratory, Dr Mark Blaygrove tests how different noises
13:48affect sleeping volunteers.
13:51Electrodes attached to the scalp allow Mark to monitor Sarah's brainwaves.
14:06Right, goodnight.
14:14Mark waits until she begins rapid eye movements.
14:17That's a sign that she's dreaming.
14:20Then he tests her sense of hearing by seeing what effect sounds have on her dreams.
14:29It's 25 minutes past four.
14:32She's quite probably dreaming at the moment.
14:35Then we're going to play her the sounds and then turn the sounds off
14:40and then wait for another two or three minutes and then wake her up again.
14:46First, she gets a burst of seagulls.
14:53Sarah sleeps through the noise,
14:55but Mark wants to know whether it's had any effect on her dreams.
15:00Hi, Sarah.
15:03Hi.
15:05Can you tell me what was going through your mind just before we woke you?
15:10Um, I was on a hilltop.
15:13Uh-huh.
15:14It was windy. Leaves blowing everywhere.
15:19The relaxing sound of seagulls has little effect on her.
15:23It just prompts pleasant dreams of going for a stroll on a windy day.
15:29By the small hours of the morning, Sarah is asleep again,
15:33and it's the ideal moment to test a very different kind of sound.
15:37So what we're going to do is to play a rather threatening voice,
15:41a police siren, and see what happens.
15:46The sirens are no louder than the seagulls,
15:49and for a while she sleeps through the noise.
15:53Then it wakes her up,
15:55but was she aware of the siren while she was still asleep?
16:01Hi, Sarah.
16:03Hi.
16:05Can you tell me what was going through your mind just before we woke you?
16:10Um, I was on a hilltop.
16:13Hi.
16:15Was there anything going through your mind just before you were woken up?
16:19Yeah, um, ambulances.
16:22Right.
16:24There was a building that was on fire. Smoke everywhere.
16:27Right.
16:35Amazingly, even while she was asleep,
16:38Sarah could hear the sirens and they triggered vivid dreams,
16:42and eventually this sound convinced her sleeping brain to wake up.
16:48It's important that we can hear while we're asleep,
16:51in evolutionary terms, just in case anything dangerous is happening.
16:56Day and night, our sense of hearing is on alert,
17:00and threatening sounds can jolt us out of our slumbers.
17:07We're extremely sensitive to sounds that warn us of danger
17:11and sounds that suggest we're in the presence of a promising mate.
17:15But sounds can be about far more than danger and sex.
17:19There's a sound some animals create
17:21designed to influence their fellow creatures' feelings in astonishing ways.
17:26It's the sound of music.
17:30I've come to Hawaii to listen to one of the most haunting animal sounds in the world
17:36to help me understand what music can do to us.
17:48Every year, thousands of them gather here
17:51in the warm waters around the Hawaiian islands
17:54to sing their hearts out.
17:56And there, those are the animals I've come to hear, humpback whales.
18:11Just like a piece of classical music,
18:14their songs contain endless variations on a theme.
18:18These animals have songs as complex as any symphony.
18:22They expend an extraordinary amount of energy singing.
18:26Some of the songsters, they can do it nearly every day for four or five months.
18:38Jim Darling studies the humpback whales.
18:41Using an underwater microphone, he can record the sounds
18:45He studies the humpback whales.
18:47Using an underwater microphone, he can pick up their songs from miles away.
18:59Jim, it's the first time I've heard a whale concert live like this.
19:04I mean, why are they singing so beautifully?
19:07The males are always getting together.
19:09They're always meeting, they're always touching base,
19:12they're always shifting positions.
19:14They're very social amongst themselves.
19:17Somehow, the song is related to that continual,
19:20almost sort of incessant male-male interaction.
19:24The songs seem to be the most effective way
19:27the whales have to convey their feelings
19:30and to influence how other whales feel about them.
19:34Whoo-hoo!
19:36Did you see that breach?
19:39This is so exciting. We're right in the middle of a pod now.
19:45Nobody's quite sure why the whales sing,
19:48but in the mating season, the males form small groups
19:51and they seem to use song to win over strangers or warn off rivals.
20:04And for us too, music is all about expressing our emotions
20:09and influencing each other's feelings.
20:19With music, we can convey an astonishing range of feelings
20:23we just couldn't express any other way.
20:34MUSIC PLAYS
20:42Music...
20:46..in its simplest form...
20:50..boils down to one thing...
20:54..rhythm.
20:56WHISTLE BLOWS
21:04CLICKS
21:08Music taps into an instinctive response we all have to rhythms.
21:13From an early age, some rhythms really get us going.
21:17Get an infant to tap to a beat
21:19and they naturally settle on a rhythm close to their resting heart rate,
21:23between one and two beats a second.
21:26And anything faster tends to make us feel up and energised.
21:31Scientists think it's because in our minds
21:33it feels like we're hearing our own hearts beating faster
21:37and that makes us feel excited.
21:46But music can do far more than just make us feel happy or sad.
21:50It can set off a whole spectrum of emotions.
21:53Almost instantly, we can sense the mood of a piece of music
21:57and it triggers those feelings within us.
22:02Yeah, it's melancholy because he's sad, but it's a nice sadness.
22:12Oh, I'm really depressed now.
22:15Very sad.
22:17MUSIC CONTINUES
22:27This is cool. It's cool music.
22:37Very soothing, relaxing.
22:45Funky. Get up and go.
22:51We all naturally react to a beat,
22:54but we also learn to associate certain musical sounds with strong emotions.
23:01So if you've grown up listening to classical music,
23:04then for you, this is powerful stuff.
23:24MUSIC CONTINUES
23:32Or maybe this moves you more.
23:42Put a great rhythm with a piece of music you know well
23:45which has strong associations for you
23:47and it becomes a sound that can trigger surprisingly intense feelings.
23:53By scanning people's brains, scientists have recently discovered
23:57that a favourite piece of music can activate the pleasure centres
24:01as much as food or sex.
24:06What we hear can have incredible effects on us.
24:11Sounds can turn us on or send us running.
24:17They can make us jump for joy or feel intense sorrow.
24:22But as well as that, there are even sounds that can make us feel like this.
24:40If you're looking for the ultimate sound hit, there's one final ingredient.
24:44Whether it's the roar of a jet engine...
24:48Opera singers belting it out...
24:51The cheers of a crowd...
24:54Or just plain old rock and roll.
24:57The sounds that have the most impact on us, they've all got one thing in common.
25:07They are loud.
25:10So why is listening to music at full volume so pleasurable?
25:14To find out, I'm going to expose my ears to a wall of sound
25:18provided by rock legend Status Quo.
25:21Rick Francis, Status Quo, one of the loudest rock bands in the world.
25:27Do you play louder towards the end of a concert or is it always the same?
25:31It does gradually get louder. We crank it up on there and it turns us on.
25:35But it's not as loud for us as it is for the audience.
25:38I was going to ask that it's not as noisy up there.
25:40No, no, no. They get the brunt of the PA.
25:43The objective is to turn them on and make them move.
25:47And you get the volume right, it should do that.
25:50Otherwise you best retire.
25:57It might seem pretty obvious that loud sounds will get us going more than quiet ones.
26:02But the reason why ear-splitting noises give us such a rush of pleasure
26:07is that loud sounds have a special effect...