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0:00:02 > 0:00:05- Every single second of every day...
0:00:05 > 0:00:09- ..our senses gather information - about our environment.
0:00:09 > 0:00:14- The senses connect us - to our surroundings.
0:00:14 > 0:00:17- I'm Dr Anwen Rees, - a Physiology lecturer...
0:00:17 > 0:00:20- ..at Cardiff Metropolitan - University.
0:00:21 > 0:00:27- I'm Dr Katie Hemer, a Bioarchaeology - specialist at Sheffield University.
0:00:27 > 0:00:31- We will look at the way the brain - uses information...
0:00:31 > 0:00:34- ..to create - a unique picture of the world.
0:00:35 > 0:00:39- We will look at familiar - and unfamiliar senses...
0:00:39 > 0:00:41- ..and how they collaborate.
0:00:41 > 0:00:43- And how to trick them.
0:00:49 > 0:00:53- HEARING
0:01:03 > 0:01:05- The modern world is noisy.
0:01:05 > 0:01:09- The auditory system - must listen to everything...
0:01:09 > 0:01:13- ..so how does it decide - what's important and what to ignore?
0:01:13 > 0:01:17- How important is hearing - in our everyday lives?
0:01:18 > 0:01:20- Most of the ear - is inside the head.
0:01:21 > 0:01:24- When we hear a sound, - the outer ear - the pinna...
0:01:25 > 0:01:29- ..captures and channels the sound - from the air into the ear canal.
0:01:30 > 0:01:35- Sound travels along the canal - until it reaches the ear drum.
0:01:35 > 0:01:38- The sound causes the ear drum - to vibrate.
0:01:39 > 0:01:43- These vibrations are then - amplified by the ossicles...
0:01:43 > 0:01:45- ..the smallest bones in the body.
0:01:46 > 0:01:48- The hammer - is attached to the ear drum.
0:01:49 > 0:01:51- As it vibrates, it hits the incus...
0:01:51 > 0:01:55- ..which hits the stapes - against the cochlea.
0:01:55 > 0:01:58- The cochlea - looks like a snail's shell...
0:01:58 > 0:02:03- ..and it's full of fluid and - thousands of cells covered in hairs.
0:02:03 > 0:02:08- Vibrations make waves travel through - the fluid and move the hairs.
0:02:08 > 0:02:12- This sends nerve signals - down the auditory nerve...
0:02:12 > 0:02:14- ..to the auditory cortex - in the brain.
0:02:15 > 0:02:19- It's like a computer, - deciphering signals as sounds.
0:02:25 > 0:02:28- One in six people in Wales - has a hearing problem.
0:02:28 > 0:02:32- How does someone with - hearing problems sense the world?
0:02:34 > 0:02:37- The Audiology Department - at Singleton Hospital...
0:02:39 > 0:02:43- ..will create a pair of plugs for me - which replicate hearing loss.
0:02:44 > 0:02:46- I can hear my voice in my head.
0:02:48 > 0:02:52- Hearing loss is a gradual process - which we rarely notice.
0:02:52 > 0:02:55- These plugs - won't block out all sound.
0:02:55 > 0:03:00- They're the equivalent - of me losing 25% of my hearing.
0:03:00 > 0:03:03- I'll try out these plugs - in the middle of Swansea.
0:03:10 > 0:03:13- What happens to sound - once it reaches the brain?
0:03:14 > 0:03:17- With so many different noises - around us...
0:03:17 > 0:03:21- ..the brain decides what - to listen to and what to ignore.
0:03:21 > 0:03:23- How does the brain do this?
0:03:23 > 0:03:28- What factors affect our ability - to focus our hearing?
0:03:28 > 0:03:33- I've come to Bangor University to - take part in some special research.
0:03:34 > 0:03:37- Dr Patricia Bestelmeyer - and her team...
0:03:37 > 0:03:41- ..look at how the brain copes - with different accents.
0:03:42 > 0:03:44- My research is on voice perception.
0:03:44 > 0:03:47- I'm interested in - how somebody conveys...
0:03:47 > 0:03:51- ..the emotional state of a speaker, - in vocal attractiveness...
0:03:51 > 0:03:53- ..and in accents.
0:03:53 > 0:03:58- I'm particularly interested in what - the sound of our voice tells us...
0:03:58 > 0:04:00- ..about that person.
0:04:01 > 0:04:05- To find out what happens in my brain - when I hear accents...
0:04:05 > 0:04:07- ..I must wear a special cap.
0:04:10 > 0:04:12- We place gel in the holes...
0:04:13 > 0:04:17- ..to help the electrodes read the - brainwaves which come off the scalp.
0:04:18 > 0:04:20- The gel is cold, - so it may feel strange.
0:04:21 > 0:04:22- Yes, it is cold!
0:04:23 > 0:04:25- It's horrible!
0:04:25 > 0:04:28- I really don't like that feeling.
0:04:32 > 0:04:35- It feels like someone cracked eggs - all over my head.
0:04:37 > 0:04:41- This technique is called EEG - and it looks at brain activity.
0:04:43 > 0:04:46- Some 126 electrodes - are attached to the cap.
0:04:48 > 0:04:51- Each electrode - records a different signal.
0:04:53 > 0:04:56- The readings will give - the researchers an idea...
0:04:56 > 0:05:00- ..of which parts of my brain respond - and when.
0:05:00 > 0:05:05- What you see is your brainwaves, - which we read from the electrodes.
0:05:05 > 0:05:09- Look at the screen and you'll see - a white cross in the middle.
0:05:10 > 0:05:12- When the cross changes - from white to red...
0:05:13 > 0:05:17- ..press the space bar - as quickly as possible.
0:05:20 > 0:05:23- Looking at the cross - should keep me alert.
0:05:24 > 0:05:28- I must listen to the word 'pamphlet' - being said hundreds of times...
0:05:29 > 0:05:31- ..in different accents.
0:05:35 > 0:05:36- That was interesting.
0:05:37 > 0:05:41- I heard three strong accents - - English, a Caernarfon accent...
0:05:42 > 0:05:46- ..and someone who sounded like - an old school friend of mine.
0:05:46 > 0:05:50- That's the accent to which - I responded most strongly.
0:05:52 > 0:05:54- The research is in its infancy.
0:05:55 > 0:06:00- It's based on the results - of Dr Bestelmeyer's previous work.
0:06:00 > 0:06:04- We found increased activation - to their own accents...
0:06:04 > 0:06:07- ..but decreased activation - to the other accents.
0:06:08 > 0:06:11- We found an interaction - between where the person's from...
0:06:11 > 0:06:14- ..and the accent they listened to.
0:06:14 > 0:06:16- We're not sure if it happens...
0:06:16 > 0:06:19- ..because your own accent - is more attention-grabbing...
0:06:20 > 0:06:23- ..or if you like what you hear - better in your own accent.
0:06:25 > 0:06:30- The brain seems to react positively - to a familiar accent...
0:06:30 > 0:06:33- ..but less so to other accents.
0:06:34 > 0:06:38- The hearing and the part of the - brain which deals with emotion...
0:06:39 > 0:06:42- ..seem to be linked - when we hear a familiar accent.
0:06:46 > 0:06:48- Oh!
0:06:50 > 0:06:55- We'll let Katie wash her hair while - I get used to my plugs in Swansea.
0:06:55 > 0:06:58- These plugs mimic a hearing loss.
0:06:59 > 0:07:03- I'm in a busy square and - I can hear a TV, water gushing...
0:07:04 > 0:07:07- ..traffic and people talking.
0:07:08 > 0:07:10- These plugs have changed the sounds.
0:07:11 > 0:07:13- I can still hear the water - and the TV...
0:07:13 > 0:07:16- ..but the traffic is very muffled...
0:07:16 > 0:07:19- ..and I can't really hear - people talking.
0:07:20 > 0:07:24- Now I'll see how it feels - to be in a busy indoor market...
0:07:24 > 0:07:27- ..trying to do some shopping.
0:07:27 > 0:07:29- SILENCE
0:07:33 > 0:07:36- Hi! A small tub of cockles, please.
0:07:37 > 0:07:38- Thank you.
0:07:39 > 0:07:42- Rhubarb and custard - and pear drops, please.
0:07:45 > 0:07:46- It was OK.
0:07:47 > 0:07:51- I can hear my voice in my head, - although it feels like I'm mumbling.
0:07:52 > 0:07:57- Every other voice seems muffled too - but I can understand them.
0:07:58 > 0:08:03- I'm here to meet Glenys Jones - from Action On Hearing Loss Cymru...
0:08:04 > 0:08:09- ..to see how my experiences - compare to people with hearing loss.
0:08:09 > 0:08:12- There are different levels - of hearing loss.
0:08:13 > 0:08:16- Mild, moderate, severe - and profound deafness.
0:08:17 > 0:08:21- I think your hearing loss - was between mild and moderate.
0:08:22 > 0:08:25- Unfortunately, - hearing deteriorates with age...
0:08:26 > 0:08:28- ..and it gets worse as we get older.
0:08:31 > 0:08:36- When I had those moulds in my ears, - my hearing was impaired instantly.
0:08:36 > 0:08:40- In reality, - deterioration in hearing happens...
0:08:40 > 0:08:43- ..over a period of months or years.
0:08:43 > 0:08:46- Yes, and it depends - on the individual.
0:08:47 > 0:08:52- Some people take up to ten years - to do something about their hearing.
0:08:53 > 0:08:57- Are increasing numbers of people - suffering hearing loss?
0:08:57 > 0:09:00- Yes, and we're now - targeting youngsters...
0:09:00 > 0:09:05- ..because we predict they'll suffer - hearing loss at a younger age.
0:09:07 > 0:09:12- They listen to loud music and that - really isn't good for the hearing.
0:09:14 > 0:09:18- How can we tell from which direction - sound is coming?
0:09:19 > 0:09:22- The brain cancels out - all the echoes...
0:09:23 > 0:09:27- ..so that we only hear - the accurate version of the noise.
0:09:29 > 0:09:32- The University Of Nottingham - has a special room...
0:09:33 > 0:09:35- ..which eliminates echoes.
0:09:35 > 0:09:38- It's known as an anechoic chamber.
0:09:40 > 0:09:44- Any noise sounds hollow, flat - and dead in this room.
0:09:48 > 0:09:51- I'm here to see - how well I can locate sound.
0:09:51 > 0:09:54- The brain works out - the direction of a sound...
0:09:56 > 0:09:59- ..by measuring - the time difference...
0:09:59 > 0:10:02- ..between the moment - sound reaches both ears.
0:10:02 > 0:10:07- If the sound comes from over here, - it will reach this ear first...
0:10:07 > 0:10:10- ..then it will reach my other ear.
0:10:10 > 0:10:16- The brain uses this information - to calculate the sound's direction.
0:10:24 > 0:10:26- In this test, sound is played...
0:10:27 > 0:10:30- ..and I move the red dot - to where I think it originated.
0:10:32 > 0:10:33- I was close!
0:10:33 > 0:10:35- Very good.
0:10:35 > 0:10:40- In the chamber, they can mimic how - noise sounds in a room of any size.
0:10:40 > 0:10:43- In the test, - I hear two different noises.
0:10:43 > 0:10:47- One sound seems to come from - an ordinary living room...
0:10:47 > 0:10:52- ..and the other is very echoey, - like a cathedral.
0:10:54 > 0:10:56- I don't know.
0:10:56 > 0:10:58- It came from everywhere!
0:11:01 > 0:11:03- I'll go over here.
0:11:05 > 0:11:07- Ah! The other side.
0:11:07 > 0:11:08- Oh, dear!
0:11:09 > 0:11:11- I may have a problem with my ears.
0:11:13 > 0:11:14- This test isn't easy.
0:11:18 > 0:11:20- No! The other side again.
0:11:21 > 0:11:23- I'm not doing very well!
0:11:23 > 0:11:27- I'm struggling because, - in an ordinary room...
0:11:27 > 0:11:32- ..the brain distinguishes between - the original sound and an echo.
0:11:33 > 0:11:36- In a large space, - like a cathedral...
0:11:36 > 0:11:40- ..the sound and the echoes - reach the ear at the same time.
0:11:40 > 0:11:45- That's why the brain struggles - to locate the original sound.
0:11:47 > 0:11:48- This is hard!
0:11:49 > 0:11:54- I found it difficult but there's - nothing wrong with my hearing.
0:11:55 > 0:12:00- We're rarely in a situation where - there are so many echoes around us.
0:12:00 > 0:12:05- Studying the way we locate sound - helps people who struggle to do it.
0:12:05 > 0:12:09- People such as those - who have had cochlea implants.
0:12:12 > 0:12:13- .
0:12:17 > 0:12:17- Subtitles
0:12:17 > 0:12:19- Subtitles- - Subtitles
0:12:22 > 0:12:26- The hearing system starts to work - before we're born.
0:12:27 > 0:12:32- Fetuses start to listen to voices - and sounds when they're in the womb.
0:12:33 > 0:12:38- Generally, humans hear frequencies - of between 20Hz and 20,000Hz.
0:12:38 > 0:12:41- This is known - as the pitch of the sound.
0:12:42 > 0:12:47- As we get older, our capacity to - hear higher frequencies diminishes.
0:12:49 > 0:12:52- The intensity of a sound - is measured in decibels.
0:12:52 > 0:12:54- Our ears are very sensitive.
0:12:54 > 0:12:59- They pick up everything, from - rustling leaves to police sirens.
0:12:59 > 0:13:03- Anything which is louder than this - can damage the hearing.
0:13:04 > 0:13:06- The Eustachian tube...
0:13:06 > 0:13:10- ..connects the middle ear - to the back of the throat.
0:13:10 > 0:13:14- It maintains normal air pressure - in the middle ear.
0:13:14 > 0:13:17- When that pressure changes, - for example in water...
0:13:18 > 0:13:21- ..holding your nose and blowing - gets it back to normal.
0:13:28 > 0:13:33- Playing football without using your - sight sounds impossible to me...
0:13:34 > 0:13:39- ..but, using their hearing, the boys - behind me make it look easy.
0:13:43 > 0:13:46- This special centre in Hereford...
0:13:46 > 0:13:50- ..is where the England - Blind Football team trains.
0:13:52 > 0:13:55- The players rely on their hearing.
0:13:56 > 0:14:00- The ability to focus - on different sounds is vital.
0:14:01 > 0:14:06- The ball rattles, and - acoustic boards around the pitch...
0:14:06 > 0:14:11- ..help players determine their - own position and locate each other.
0:14:14 > 0:14:18- As players go in for a tackle, - they must shout, "Voy!"
0:14:18 > 0:14:24- In addition, they listen for - instructions from the goalkeeper...
0:14:25 > 0:14:28- ..the coach on the touchline - and the manager.
0:14:30 > 0:14:35- I invited former Wales international - footballer, Iwan Roberts...
0:14:35 > 0:14:37- ..to have a go at playing the game.
0:14:38 > 0:14:42- Iwan, what did you make of - that training session?
0:14:42 > 0:14:44- These lads are incredible.
0:14:44 > 0:14:48- They run at pace, - keeping the ball under control.
0:14:48 > 0:14:52- I'm nervous but I look forward - to taking part in the session.
0:14:52 > 0:14:54- Put these over your eyes.
0:14:57 > 0:14:59- I can't see a thing.
0:14:59 > 0:15:00- You look great!
0:15:03 > 0:15:06- The first step is to get used to - the size of the pitch.
0:15:07 > 0:15:10- In other words, - the distance between the boards.
0:15:10 > 0:15:13- Iwan is ready - to train with the ball.
0:15:15 > 0:15:19- Put your head above the ball. - You're leaning back.
0:15:24 > 0:15:26- Keryn Seal from Bridgend - is the captain.
0:15:27 > 0:15:31- When I was partially sighted, - hearing was my secondary sense.
0:15:31 > 0:15:35- When I went to being a blind - footballer, it was a huge jump.
0:15:35 > 0:15:38- It's not like - your hearing gets any better.
0:15:38 > 0:15:42- It's not like you can hear - a pin drop from 1,000 yards.
0:15:42 > 0:15:44- You learn to use it better...
0:15:44 > 0:15:48- ..so it's able to process - three, four, five stimuli at once.
0:15:48 > 0:15:52- It's hard to get used to because - you're trying to focus on the ball.
0:15:52 > 0:15:55- But now, I process - the information around me...
0:15:56 > 0:16:00- ..and the ball is secondary to that - because I practise skills so much.
0:16:00 > 0:16:04- To be fair, Iwan seems to be - picking it up quickly.
0:16:05 > 0:16:08- The experience - of watching the boys train...
0:16:08 > 0:16:11- ..was better - than when I first took part!
0:16:13 > 0:16:15- I couldn't see where I was going.
0:16:15 > 0:16:19- I knew there were boards - on the side of the pitch...
0:16:20 > 0:16:24- ..and my arm came out, as I - wasn't sure where the boards were.
0:16:24 > 0:16:27- I was worried about those boards.
0:16:28 > 0:16:31- Would you like to take part - in a game?
0:16:31 > 0:16:32- No!
0:16:33 > 0:16:36- The tempo of their play - is incredible.
0:16:36 > 0:16:40- They have speed on the ball - and the tackles do come flying in!
0:16:41 > 0:16:42- I'll leave them to it.
0:16:58 > 0:17:01- The sun has set in - the Swansea University gardens...
0:17:01 > 0:17:03- ..and we're looking for bats.
0:17:04 > 0:17:10- Dr Gethin Thomas will show me - how bats use their hearing...
0:17:11 > 0:17:13- ..in a very special way.
0:17:13 > 0:17:17- Gethin, what is that device - you're holding?
0:17:17 > 0:17:21- It's a device which makes it - possible for us to hear bats.
0:17:22 > 0:17:27- The frequency of bat calls is - too high for human ears to hear.
0:17:27 > 0:17:29- What will we hear from the bats?
0:17:29 > 0:17:31- What will we hear from the bats?- - A series of clicks.
0:17:31 > 0:17:36- The sound we'll hear from this will - be a click, click, click, click.
0:17:36 > 0:17:39- We may also hear - a faster sequence...
0:17:39 > 0:17:42- ..which sounds like - blowing a raspberry!
0:17:43 > 0:17:44- CLICKING
0:17:45 > 0:17:47- We're hearing a sonic attack.
0:17:48 > 0:17:53- The bat is only a centimetre or two - away from the butterfly...
0:17:53 > 0:17:56- ..and this sonic attack - stuns the butterfly...
0:17:57 > 0:17:59- ..making it easier to catch.
0:17:59 > 0:18:02- Are we hearing - bats echolocating here?
0:18:02 > 0:18:04- Yes, that's right.
0:18:04 > 0:18:08- Bats use sound in the same way - as aeroplanes use radar.
0:18:08 > 0:18:11- They emit sound, - then they listen for echoes.
0:18:11 > 0:18:15- That echo helps them work out - what's around them.
0:18:23 > 0:18:26- With practise, - people can also echolocate.
0:18:27 > 0:18:29- HE CLICKS HIS TONGUE
0:18:30 > 0:18:34- Robert Williams went to America - to learn this technique.
0:18:36 > 0:18:38- Passive echolocation...
0:18:38 > 0:18:43- ..is something people use daily - without thinking about it.
0:18:43 > 0:18:47- I learned to click - and it's a more direct method.
0:18:50 > 0:18:54- The noise stops here, - so I know the post is here.
0:18:55 > 0:18:57- I'll go out again.
0:18:58 > 0:18:59- Another post.
0:19:00 > 0:19:05- Every noise we make creates echoes - and we hear them all the time.
0:19:05 > 0:19:07- We don't think about it.
0:19:07 > 0:19:09- It just happens naturally.
0:19:11 > 0:19:14- If you're at home and you hear - the front door open.
0:19:14 > 0:19:18- You don't see the front door. - You just hear it.
0:19:18 > 0:19:20- That's echolocation.
0:19:20 > 0:19:25- Being in America made me more aware - of it but I've used it all my life.
0:19:27 > 0:19:30- Robert says anyone - can learn this technique...
0:19:30 > 0:19:33- ..so he'll give me - an echolocating lesson.
0:19:35 > 0:19:37- Shh.
0:19:39 > 0:19:40- Can you hear the difference?
0:19:40 > 0:19:41- Can you hear the difference?- - Yes.
0:19:42 > 0:19:44- Hiss without your hand there.
0:19:44 > 0:19:45- Shh.
0:19:46 > 0:19:48- It now sounds hollow.
0:19:48 > 0:19:52- Yes, it's obvious that there's - an empty space in front of me.
0:19:52 > 0:19:57- If I stand right in front of you, - you'll hear a difference again.
0:19:59 > 0:20:01- Shh.
0:20:03 > 0:20:04- Yes - it's very clear.
0:20:04 > 0:20:07- Yes - it's very clear.- - You know there's a big lump ahead!
0:20:08 > 0:20:11- Next, you must learn - to make a better sound than shh!
0:20:11 > 0:20:14- The usual way - is to click the tongue.
0:20:19 > 0:20:24- You're producing two sounds. - It's like a classic clip-clop sound!
0:20:24 > 0:20:28- Move your tongue further back - and click faster.
0:20:32 > 0:20:35- That's better. It's a bit sharper.
0:20:37 > 0:20:39- Next, I'll use my click...
0:20:39 > 0:20:44- ..to work out on which side - of my head Robert has put his arm.
0:20:45 > 0:20:47- SHE CLICKS HER TONGUE
0:20:49 > 0:20:51- The left side.
0:20:51 > 0:20:52- The left side.- - Well done.
0:20:53 > 0:20:54- Correct!
0:21:03 > 0:21:05- I think it's the left again.
0:21:06 > 0:21:07- Oh! The right.
0:21:07 > 0:21:09- No arm at all!
0:21:11 > 0:21:15- How do you use echolocation - in your everyday life?
0:21:17 > 0:21:21- I couldn't do without it - but my stick is more important.
0:21:22 > 0:21:26- There are times when I do use - echolocation to help me.
0:21:26 > 0:21:31- Sometimes on the street when there - are lots of lamp posts around.
0:21:31 > 0:21:34- Echolocation helps me - in those situations.
0:21:36 > 0:21:40- Robert shows me an example - of the way distance changes echoes.
0:21:42 > 0:21:44- What can you hear?
0:21:44 > 0:21:46- What can you hear?- - There's something in front of me.
0:21:46 > 0:21:48- How close is it?
0:21:50 > 0:21:52- Around half a metre away.
0:21:54 > 0:21:55- Carry on.
0:21:55 > 0:21:56- Will I walk into a wall?
0:21:56 > 0:21:57- Will I walk into a wall?- - Stop!
0:21:58 > 0:21:59- How close is it now?
0:22:01 > 0:22:02- Really close.
0:22:02 > 0:22:03- Really close.- - Touch it.
0:22:06 > 0:22:08- I knew there was something there.
0:22:09 > 0:22:11- SHE GIGGLES
0:22:11 > 0:22:13- Stop!
0:22:14 > 0:22:15- Go!
0:22:18 > 0:22:20- I'm facing outside.
0:22:20 > 0:22:21- I'm facing outside.- - Well done.
0:22:23 > 0:22:24- Very good.
0:22:25 > 0:22:27- Today was a good start...
0:22:27 > 0:22:32- ..but I needs lots of practise - if I'm going to master echolocation.
0:22:32 > 0:22:37- One thing's for certain - I'll - listen more carefully from now on.
0:22:40 > 0:22:42- How important is hearing to you?
0:22:43 > 0:22:45- Hearing is everything to me.
0:22:45 > 0:22:47- Everything.
0:22:47 > 0:22:50- I can't imagine life - without hearing.
0:22:54 > 0:22:56- It's part of everything I do.
0:22:56 > 0:22:58- I'm a musician and I love to talk!
0:23:00 > 0:23:03- I use my hearing - to get around the country.
0:23:04 > 0:23:07- Hearing is incredibly important - to me.
0:23:14 > 0:23:18- We're surrounded by sound - in the modern world.
0:23:18 > 0:23:23- The brain must recognize the sound - and decide if it's important...
0:23:24 > 0:23:27- ..and get rid of echoes - so we can locate it.
0:23:27 > 0:23:31- Learning to listen - changes the way we hear the world.
0:23:35 > 0:23:39- Next time, we find out - about our sense of touch...
0:23:41 > 0:23:43- ..and we feel pain.
0:23:58 > 0:24:00- S4C subtitles by Eirlys A Jones
0:24:00 > 0:24:01- .