"ln this episode of the human senses we.re looking at the strange things that go on inside our ears." "And how the tiny system of bony tubes in the inner ear evolved to carry out 2 separate senses, hearing and balance." "We.ll see what happens when you push your sense of balance right too the edge." "We.ll discover why acrobats fall down when the lights go out." "And how astronauts learn to find their feet in a weight less world." "And in the Florida swamps we.ll be finding out about the origins of our sense of hearing." "We.ll uncover the sounds, which have the most powerful effects on us." "Prepare yourself for an auditory assault course." "And you.ll discover why a loud rock concert can really blow your mind." "The sounds we hear can have amazing effects on us." "change the music and these menacing killer sharks are transformed in to beautiful wonders of nature." "so which are they?" "These are caribbean reef sharks and even though they may nip they certainly aren.t man-eaters." "Without the scary sound track the sharks don.t seem as menacing." "That.s the power of sound." "We.re going to discover how our sense of hearing can really have an incredible effect on how we experience the world around us." "We live in a world of constant noise." "Most of it just washes over us." "But some sounds cut right through the din and effect us deeply." "If we.re after the sounds with the most powerful effects on us where better to start than with the ones that hit a raw nerve." "What if you had to be bombarded with all the most unpleasant sounds." "What do you think would be top of the list?" "There.s all that every day noise pollution." "Those loud incessant sounds that do your head in." "Then there are those harsh sounds that can be hard to ignore." "Babies whaling." "some people find some noises even more unpleasant than that." "car alarms, yeah they (peep ) me off." "car alarms." "that.s obnoxious, absolutely obnoxious." "oh l hate that. oh you want to shoot them?" "All very unpleasant." "But in surveys of the noises people hate most there.s one sound, which beats all these." "You might want to turn the volume down for this one." "Even the thought of it is deeply unpleasant." "No" "That.s nasty actually." "These people are about to hear the world.s most annoying sound." "oh no, don.t." "oh." "noise it is it is horrendous." "The sound of fingers on a blackboard is almost unbearable." "A bit of noise can have such an astonishingly powerful effect on us its quite extraordinary." "When you stop to think about what sound consists of." "sounds are just tiny movements of the air molecules around us." "But our ears contain a wonderful system for detecting these faint ripples in the air." "First the sound waves are funneled down the ear cannel to the eardrum." "If they were slowed down massively this is what they.d look like." "The moving air makes the eardrum vibrate." "These vibrations are then amplified by 3 hinged bones." "The bones are connected to a tube called the choclea, which is full of fluid." "The vibrations of the bones send ripples through the fluid, and these ripples move rows of microscopic hair cells." "As the hair cells are bent they send nerve signals to the brain, which then works out what the sound is." "lt.s an extraordinary contraption but it works beautifully." "We.re equipped with a fantastic system for hearing a phenomenal range of sounds." "But out of all the noises we hear why do we respond so strongly to a few particular kinds of sound?" "For us Humans just the sound of another human voice can be a real turn on." "At the third beat will be 1 0 past 1 2." "Behavioural expert sarah collins has been studying how the sounds of some voices can work wonders." "on the third beat it will 1 0 past 1 2." "At the third beat it will be 1 0 past 1 2." "At the third beep it will 1 0 past 1 2." "so in a few seconds you.re going to hear a male voice." "While he.s speaking I want you to think about it carefully and afterwards l.ll ask you a few questions about what you think of that voice." "ok." "At the third beep it will 1 0 past 1 2." "A rich deep voice yes." "Public voice." "At the third beep it will be 1 0 past 1 2." "sounds like quite an attractive voice." "lt.s quite deep." "At the third beep it will be 1 0 past 1 2." "lts hardly love poetry but his voice alone is conjuring up vivid images." "Probably quite a large body build." "Dark hair, thick hair." "Probably tall and big hands." "sarah collins has found that most women imagine that men with rich deep voices are more muscular, attractive and even have hairier chests than their higher voiced counterparts." "If a man has a deeper voice, the kind of assumptions women make about that man, tend to be that he.s slightly more dominant." "That he is somehow more masculine, more likely to have bristles." "ls more likely to big and beefy." "At the third beep it will be 1 0 past 1 2." "Quite sexy" "And the effect seems to work the other way too." "A husky female voice can really get a mans imagination going." "At the third beep it will be 1 0 past 1 2." "so what did you think of that voice then?" "That was quite an attractive voice." "I think it sounds pretty sexy actually, yeah." "I think she.ll be quite curvy." "Er not to tall but just about right." "Yeah associated with maybe being er quite frisky" "Well I think the reason that men find husky voices attractive is simply because if somebody.s sexually aroused then their voices get more husky." "so huskiness just has yeah, makes you think of somebody being sexually aroused." "But voices can be deceptive." "Most of us are actually surprisingly bad at predicting what people will look like at from the sound of their voice." "Annoying noises we can.t stand or warm inviting voices." "sounds that get too us." "But sometimes things we hear can cut through even when we.re totally unconscious." "There are times when a good sense of hearing can be a matter of life and death." "ln the day our monkey ancestors used their eyes to detect predators." "But at night they relied on their ears." "And every night when all our other sense have shut down our hearing is still on the alert for danger." "Dr Mark Blagrove tests how different noises effect sleeping volunteers." "Electrodes attached to the scalp allow mark to monitor sarah.s brain waves." "Right good night." "Mark waits until she begins rapid eye movements." "That.s a sign that she.s dreaming." "Then he tests her sense of hearing by seeing what effects sound have on her dreams." "its 25 minutes past 4." "she.s quite probably dreaming at the moment." "Then were going to play her the sounds and then turn the sounds off." "And then wait for another 2 or 3 minutes and then wake her up again." "First she gets a burst of seagulls." "sarah sleeps through the noise but mark wants to know whether it.s had any effect on her dreams." "Hi sarah, hi. can you tell me what was going through your mind just before we woke you?" "Erm l was on a hilltop." "Huh huh." "And it was windy there were leafs blowing everywhere." "The relaxing sound of seagulls has little effect on her." "It just prompts pleasant dreams of going for a stroll on a windy day." "By the small hours of the morning sarah is asleep again." "And it.s the ideal moment to test a very different kind of sound." "so what we.re going to do is play a rather threatening noise, police siren and see what happens." "The sirens are no louder than the seagulls, and for a while she sleeps through the noise." "Then it wakes her up." "But was she aware of the siren while she was still asleep?" "Hi sarah hi." "Was anything going through your mind just before you were woken up?" "Yeah erm ambulances." "Right." "There was a building that was on fire, smoke everywhere." "Right." "Amazingly even while she was asleep, sarah could hear the sirens and they triggered vivid dreams." "And eventually this sound convinced her sleeping brain to wake up." "lts important that we can hear while we.re asleep." "ln evolutionary terms just in case anything dangerous is happening." "day and night our sense of hearing is on alert." "And threatening sounds can jolt us out of our slumbers." "We.re extremely sensitive to sounds that warn us of danger or sounds that suggest we.re in the prescience of a promising mate." "But sounds can be about far more than danger and sex." "There.s a sound some animals create designed to influence their fellow creatures feelings in astonishing ways." "lt.s the sound of music." "We.ve come to Hawaii to listen to one of the most haunting animal sounds in the world." "Because these creatures can help us understand what music does to us." "Every year thousands of them gather here in the warm waters of the pacific to sing their hearts out." "The animals we.ve come to hear are hump-backed whales." "Just like a piece of classical music, their songs contain endless variations on a theme." "They.re as complex as any symphony." "And the whales expend an extraordinary amount of energy singing." "some of the songsters do it nearly every day for months on end." "We.re right in the middle of a pod of whales now." "No bodies quite sure why the whales sing." "But in the mating season the males form small groups and they seem to use song to win over strangers or warn off rivals." "And for us too music is about expressing our emotions and influencing each other.s feelings." "With music we can convey an astonishing range of feelings, we just couldn.t express any other way." "Music, ln its simplest form, boils down to one thing." "Rhythm." "Music taps in to an instinctive response we all have to rhythms." "From an early age some rhythms really get us going." "Get an infant to tap to a beat and they naturally settle on a rhythm close to their resting heart rate." "Between 1 and 2 beats a second." "And anything faster tends to make us feel up and energised." "scientists think its because in our minds it feels like we.re hearing our own heart beating faster." "And that makes us feel excited." "But music can do far more than just make us feel happy or sad." "It can set off a whole spectrum of emotions." "Almost instantly we can sense the mood of a piece of music, and it triggers those feelings within us." "yeah he.s melancholy because he.s sad, but it.s a nice sadness." "urgh l.m really depressed now." "v ery sad." "This is cool, is cool music." "very soothing, relaxing." "Funky get up and go." "We all naturally react to a beat." "But we also learn to associate certain musical sounds with strong emotions." "so if you.ve grown up listening to classical music, then for you this is powerful stuff." "or maybe this moves you more?" "Put a great rhythm with a piece of music you know well which has strong associations for you, and it becomes a sound that can trigger surprisingly intense feelings." "By scanning people.s brains, scientists have recently discovered that a favourite piece of music can activate the pleasure centres as much as food or sex." "What we hear can have incredible effects on us." "sounds can turn us on or send us running." "They could make us jump for joy, or feel intense sorrow." "But as well as that are even sounds that can us feel like this." "For the ultimate sound hit, there.s one final ingredient." "Whether it.s the roar of a jet engine." "opera singers belting it out." "The cheers of a crowd." "or just plain old rock and roll" "The sounds that have the most impact on us, they.ve all got one thing in common." "They are loud." "so why is listening to music at full volume so pleasurable?" "Rock legends status Quo know very well that being loud enough is absolutely crucial." "the kind of louder it gets l suppose in a way in a way the more exciting it gets l suppose." "I mean that.s what it its suppose to do for us, I mean you know." "We crank it up on there." "And it it turns us on." "But it.s not as loud for us they get the the brunt of the PA, er which we.re behind." "I like it loud l like I like I like it rocking, and loud." "I mean its got to be at the right volume for the the hall your in, for the amount of people you.ve got a bit, you you got in there." "The objective is too turn them on and er make them move." "And you get the volume right it should do that." "otherwise you best retire." "It might seem pretty obvious that loud sounds will get us going more than quiet ones." "But the reason why ear-splitting noises give us such a rush of pleasure is that loud sounds have a special effect on our senses." "Inside our heads next to the tiny choclea which allows us to hear we have a set of structures designed to sense how our heads are moving." "one of them a ball filled with jelly called the saculus is what tells us how fast we.re excellerating" "The saculus has nothing to do with normal hearing." "But recent research suggested that at certain frequencies loud sounds can vibrate the inner ear so much that the saculus gets shaken about as if we were free falling through the air, which would explain why loud sounds can trigger a pleasure rush through the brain," "and make you feel like this." "According to the theory the sound level needs to over 90 decibels." "Loud enough to cause permanent damage, after a while." "so will the crowd respond differently when the quo when they hit 90 decibels?" "50" "70" "90 decibel.s." "When they.re hit by a wall of sound like this the audience really get carried away." "This response to sound is really due to our sense of balance getting excited." "so why is our sense of balance so closely connected to our sense of hearing?" "The answer goes back millions of years." "ln the Florida Everglades wild life expert" "Tim William.s has spent years working with a Pre historic creature." "The Alligator." "Alligators were around before the dinosaurs." "And they can tell us something about the origins of our own sense of hearing." "Amazingly all modern reptiles, birds and mammals including us have ears based on the same ancient design." "once you live on land being able to hear sounds traveling through the air is crucial for survival" "It helps parent.s keep track of their young." "lts also a good way to communicate." "To warn off rivals," "and most importantly to serenade a mate." "ln the breeding season the male alligators try to impress the females with deep bellowing." "Just behind the eye theres a flap of skin covering the entrance to the ear, which is designed just like ours." "When the first backbone animals emerged out of the water they already had all their other senses." "Hearing in air was the last sense our ancestors developed." "And it evolved as a spin off from their sense of balance." "The tiny choclea in the inner ear, which we use for sensing sound, is so closely linked to our balance organs, because the choclea literally evolved as an off shoot from these older structures." "ln the second half of the programme we.re going to discover the secrets of our sense of balance." "How we can do this?" "And even this." "But then this makes us fall over." "you fell really sick." "Everything.s just turning and turning about until you just fall to the ground." "We.ll find out why everything we do is a incredible challenge for our sense of balance." "We.ll discover how we keep track of how our bodies are moving even when the world is spinning around us." "And exactly what it takes to bring it all crashing down." "We humans are one of a very select club of creatures that get about on just their hind legs." "There are only 2 kinds of animals that spend much of their life performing the tricky balancing act of walking on 2 feet." "us and some flightless birds." "And neither of us has the ideal design for it." "If you wanted to design an animal to balance on 2 legs you wouldn.t necessarily end up with a human being or an ostrich." "An ostrich has to work really hard not to topple over." "A lot of its body weight is hanging over the front of its legs." "our body mass on the other hand is easier to handle." "With a nice upright torso with all our weight directly over our legs." "But our problem is a big heavy head at the top that can tip us over." "And if walking on 2 legs isn.t hard enough we go and make things even more difficult." "What makes life really tough for the human sense of balance is the crazy things we do with our bodies." "unlike any other animal we take pleasure in devising bizarre ways to test our sense of balance." "And because we do all this it.s a monumental challenge to keep track of where we are at all times." "The world can be a pretty confusing place." "Which way are we moving?" "Which way are we spinning?" "Which way is the right way up?" "Nln order to keep control you have to know how your body is moving through space." "And when you.re a stunt man like Marc cass being aware of your own movements is vital to the job." "lt.s really important for every stunt man to have good body co-ordination, know where they are in space." "other wise it could be a matter of life or death." "so how do we sense which way our body is moving?" "For that basic information we rely on a set of special balance organs deep within the ear." "This series of tubes and chambers no bigger than a pea monitors ever move made by our head." "so when we take off, or skid to a halt, or go in to a spin." "These movements are sensed within the inner ear." "The tubes are full of fluid." "Inside the tubes there are tufts of microscopic hair cells." "When we move our heads the fluid move and the hair cells are bent." "They send nerve signals to the brain." "The tubes point in 3 different directions." "And that.s how we can sense movement in 3 dimensions." "The balance sense in the ear tell us one other vital thing." "Which way is up," "And which way is down." "You don.t have to throw your body round that violently to test your balancing systems." "sometimes even standing upright can be a challenge." "Getting around on 2 legs means we need to know what virtually every inch of the body is doing." "so walking is an incredible challenge." "Most of the time we.re actually balancing on one foot." "As we move almost every muscle in our body is involved in a furious battle to stop us from toppling over." "so beside the balance organs in the ears we need sensors in our limbs and torso to let the brain know what the body is doing." "Within a fraction of a second the brain sends out millions of signals to the muscles to make corrections that keep us balanced." "But we.re actually born without any ability to balance upright at all." "We have to learn it through trial and error." "And it takes years before the information between our limbs and our brain is processed fast enough so it all happens smoothly." "Eventually walking becomes second nature." "But its such a complex operation that even the tiniest change can upset everything, like puberty." "With our bodies growing so fast the nerve circuitry in our brains can.t keep up with the changes to the body." "The wrong signal was sent to the limbs and so for a while we.re gawky and clumsy." "When you realise just how difficult walking is its no surprise that anything a little more tricky takes a phenomenal amount of practice." "lt.s not just our bodies we have to balance on our 2 legs." "We also pick things up and carry them around." "Doing this creates an even greater challenge for our sense of balance." "The secret of our success is that we actually prepare ourselves before we do it" "Take a look at this." "We.ve set up a simple test with a suitcase, some weights and a group of unsuspecting volunteers." "First the suitcase is filled with around 1 2 kilos of weight." "The volunteers are asked to pick up the suitcase and repeat the movement a few times." "Then we take them out of the studio and ask them a question that has nothing to do with the experiment." "so its actually an observational test." "Did you notice the colour of the camera mans T-shirt?" "Erm no." "And while the volunteer is preoccupied we replace the weighted suitcase with an empty one." "ok." "We.ll go back to the studio." "ok." "Because they don.t know that a switch has been made they automatically balance themselves for a heavy case." "so they falter but they don.t fall over." "Amazingly it takes just a fraction of a second for our sense of balance to detect what.s wrong, adjust and keep us upright." "With our top-heavy design moving around on 2 legs is a fantastic-balancing act." "We use senses in the ear and through out the body to guide constant minute adjustments to thousands of muscles." "But there.s one other vital component to our sense of balance." "We.ve come here to the circus centre in san Francisco to see it in action." "lts awe inspiring what these acrobats can do." "some of these manoeuvres take years of training." "But we.re about to see a stunt that will test even their sense of balance to the absolute limit" "They.re going to perform one of the most difficult stunts in their repertoire, the human tower." "lt.s going to take 4 people nerves of steel and a very strong foundation." "lt.s a teamwork." "Everybody should work together." "Back strong, legs strong." "Keep stay there." "Tight right." "stay tight, ok thank you good luck." "As each person is added to the tower the problems multiply." "If the tower is to stay standing, everyone has to stay as perfectly still and upright as possible." "lt.s a hair-raising test for their sense of balance." "Every detail supplied to the brain by the sensors in the inner ear and the limbs is crucial." "But it.s actually something else that.s keeping Alex team standing." "Neither the movement.s sensors in their heads or their limbs can stop the really minute wobbles." "For that they need their eyes." "Their eyes tell them when they.re swaying even slightly, because they can see the room.s moving." "so how well will they manage without their eyes?" "To find out they.ve agreed to build the tower again, but once they.re up the lights are going to be turned off." "The troop is going to attempt a tower of 3." "ok are you steady now?" "Now they.re up the lights are going to go out and we.ll switch to an infra red camera to see how they get on in the dark?" "can these masters of balance keep the tower standing in complete darkness?" "Bad luck, its so difficult to balance without the help of your eyes, that the team here reckon that no one has ever managed a tower of 4 in the dark." "ln fact we all rely on vision when it comes to keeping our balance." "standing on one leg is a bit tricky but with eyes open most of us can do it for quite a while." "But what happens when you close your eyes?" "You quickly discover how much vision is keeping you upright." "yeah l.ll loose balance a bit when I close my eyes." "Why.s that?" "our sense of balance is an extraordinary combination of 3 separate sensory systems, in our ear, our limbs and our eyes." "When they.re all working together in harmony we can even stay upright in the most testing situations." "But all of the time our balance system operates right at the limit." "so even the slightest malfunction can send us crashing to the floor." "When we move around the inner ear is normally superb at sensing the movement, but it.s actually quite a delicate system" "These junior school children have volunteered to be thrown off balance." "Games, which involve running about, and making quick turns are no problem." "But change the movement slightly and it.s a very different story." "If you keep spinning round and round the fluid in your balance organ starts to move round and round too." "The problem starts when we stop." "Alright, first it you feel like you.re moving around the earth." "But when you stop the earth seems to move round without you." "We may have stopped spinning but the fluid in the ear is still moving, so the brain thinks we.re still turning round and round." "You feel really sick." "Everything.s just turning and turning about until you just fall to the ground." "But its not just children.s games that throw us off balance, the over 1 8.s have ways too." "The world moves in a mysterious way if the signals from the balance centers in our brain are disrupted or delayed in any way." "And there.s a liquid that.s very good at doing just that, alcohol." "If we drink enough alcohol it starts to disrupt the nerve systems in the cerebellum." "That.s the brains balance centre." "lt.s the part of the brain that co-ordinates all our movements in our muscles particularly in the legs." "The alcohol level in the blood goes up and that starts to effect the cerebellum after a while, and that.s when you start to stagger." "Alcohol slows down the nerve signals from the brain to the legs, which destroys our sense of balance." "so before the advent of the breathalyser the test for drunk drivers was walking the line." "But alcohol can have a second effect on our sense of balance." "Drink enough of it an it even starts to mess with the balance organs within our inner ear, which creates a very unpleasant sensation." "lt.s called the ..screaming Horizontals... its when you put your head back, particularly if you have your eyes closed as well, but suddenly the room seems to take off." "The world starts to lurch and it makes you feel quite sick and and disorientated." "The alcohol in the blood gets in to the inner ear effecting the tiny hair cells which sense movement." "That tricks the brain in to thinking that movements are much more exaggerated than they are." "so a small move feels like a complete 360-degree head spin." "ok a little bit dizzy to be perfectly honest." "But apart from that not too bad." "We rely on our separate balance systems to work together to keep us upright." "We make life hard by throwing ourselves around like no other animal on the planet." "Even our ability to walk upright is a massive achievement for our sense of balance." "But we don.t stop there." "We.re always testing how far we can go." "And we push ourselves even further where no creature on earth was ever meant to go, by venturing in to the weightlessness of space." "But if our sense of balance is so precarious, how on earth does anyone deal with weightlessness." "We.ve come to star city in Russia to find out." "This Russian jet plane has been modified for a very special purpose." "When its air born it will do something extraordinary." "The conditions are so severe that you aren.t allowed to fly unless your bodies in tip top condition." "How am I?" "Like a cosmonaut thank you" "Now He.s passed the medical this volunteer is about to experience his first trip aboard the vomit comet." "Every child wants to experience what its like to be an astronaut floating in space." "But the vomit comet can produce extreme motion sickness - some people end up in hospital on a drip because they lose so much fluid vomiting." "to create zero gravity the pilot has to execute an enormous ark at 25,000 feet." "First the plane makes a steep climb at full throttle." "Then the powers cut and the plane arks over into a dive." "And everything on board becomes weightless." "The steep climbs and nosedives are so ferocious that according to some cosmonauts a trip on the vomit comet is tougher on our sense of balance than space itself." "There it goes theres nothing on earth that can prepare you for this." "Then plane is plummeting through the sky." "But inside the cabin it seems as though they.re just floating serenely." "With no gravity the balance sensors in the inner ear aren.t working." "And with no windows its hard to get any clues to which way is up or down." "Yet amazingly after a few goes most of these people who have never flown the vomit comet before are starting to enjoy themselves." "The secret is to decide what.s up and what.s down and to completely ignore the confused signals from the sensors in your inner ear its extraordinary how quickly our bodies can adapt to a strange New World where non-of the normal rules apply." "This must be the ultimate triumph of the senses." "To survive in an environment that sense of balance was never designed for."