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00:00 So watch on the auditory system. I'm gonna start with that. What

00:09 sound? I was like what are properties of life? But the properties

00:15 sound hearing is neural perception of sound . Sound Is traveling waves for vibrations

00:26 air molecules traveled 343 m A second 767 mph. So you can drive

00:34 fast as the sound. But you fly faster than sound in the speed

00:38 sound. And when the sound travels have these regions of compression and rear

00:47 compress. Their molecules are rare fact they're molecules. And an example is

00:53 you hit the fork and that fork vibrating the tuning fork the vibration of

00:58 fork creates the vibration of the air . It spread from that for in

01:04 forms of the compressed and we're a that weighs oscillations and and the movement

01:12 the air molecules. Likewise when you the speaker producing the sound, the

01:19 were producing the information from the phone from the record player. From the

01:25 . D. Player. From the player and it's connected to speakers and

01:32 have the star fragments. These membranes . So the faster they vibrate,

01:39 higher pitch they represent the slower to . And the larger typically the

01:44 This is a low range the subway sound low frequency range but this vibration

01:50 the membrane even in your headphones there's little tiny speaker that vibrates a tiny

01:57 and produces the sound for you And here And this is just compressed and

02:01 affected waves of air that are Human audible range is 20-20 kHzertz When

02:10 hurts 20 kHz. So these are times per second. sound oscillations up

02:16 20,000 times per second. Ultrasound is 20 kHz. A lot of marine

02:25 . A lot of dolphin fish, communicated their high frequencies and can perceive

02:32 high frequencies. We get them cut . You can sometimes perceive those very

02:37 frequencies if they cross through the barrier water to the hall of the ship

02:43 something like this, you can actually hear those high frequencies. But other

02:47 that there's a whole world of communication the water very high frequencies that we

02:53 not perceive. Infrasound below pointing hurts like our vibrations, sub warfare

03:01 If you I think actually if you're a speaker, I mean buying a

03:06 it will even say it goes down 10 birds. Why does it go

03:12 to temper? You're not going to able to hear below 20 months.

03:18 at 10 hertz and the subwoofer vibration the air movement, you're going to

03:24 able to feel it. So you be able to perceive it through this

03:27 of sensory system which is a different . And if any of you have

03:31 to a music hall club concert. you stood close to the sub

03:37 You actually feel the physical movement of molecules on your amount of sensor

03:42 19 years. So you have the and you have the loudness. This

03:50 low frequencies. The pitch. High mm. Okay low intensity. It's

04:00 same pitch but high intensity is the pitch louder. So that's what intensity

04:09 loudness and frequency is pitched. Yeah have the structure in your here.

04:20 have the outer area of the middle and the inner. Here these are

04:24 major divisions and you have the owner the air. This is out of

04:32 . And the auditory canal is also external auditory miatas that goes into the

04:38 panic membrane symphony. Just the This is your ear drum that is

04:46 to obstacles. So these are mechanical that move but the giants with each

04:53 and move the over window. So obstacles from the drum is in the

04:58 air. And then the cochlear which a part of the vestibular cochlear apparatus

05:04 the oval window. Then is in inner. Here The vestibular cochlear apparatus

05:10 the cranial nerve eight or the output uh from the tubular cokie apparatuses cranial

05:17 eight which consists of the stimulus to and cochlear component. So cochlear component

05:27 the one that is coming from the that looks sort of like a snail

05:33 up snail in humans. It's about size of a pea like snoopy.

05:41 uh Jenna external ear air wax would living here some panic membrane air

05:49 And then in the inner middle ear have the pharynx uh descending interference.

05:56 have the station too. This is station to station tube. It's used

06:03 equalizing the pressure between your outside the and the inside of the mouth.

06:09 when you're flying for example and you the elevation or if you're going down

06:15 hill or up the hill when you feeling that most often what you start

06:20 is opening your mouth may be Don't even knows and that equalizes

06:28 If you don't equalize the pressure and ascend with an airplane you can actually

06:33 pretty serious headache that forms uh And station tubes is also the side as

06:40 can see. It's beautiful. It all the way from here into the

06:45 of the throat and the banks. also the site where the infections are

06:50 . In fact take place. It's great environment. It's really moist in

06:55 back of the throat there. So lot of bacterial species. It's

07:00 moist, protected. They established themselves . And when you hear somebody had

07:08 tubes replaced and they hear that I my tubes or my child had the

07:14 replaced. The station tubes get replaced the plastic insert tubes and plastic is

07:22 a favorable environment for bacteria to But why would you do that.

07:28 if you recall? We talked about and in particular we talked about critical

07:33 of development and we look at an in visual system where one eye vision

07:40 and one eye for six days permanently the cortex during this critical period of

07:47 irreversibly. And uh I was no responsive and the cortex was no longer

07:54 to the stimulus to that. I that example. So what happens if

08:01 this critical period of development for especially our Children and publishes, they're learning

08:06 they're listening to things? You deprive of hearing in one year. You

08:12 restructure the circuits too and you ignore central pathways. Started ignoring the periphery

08:22 is clogged up. It's no longer . It's not listening. So if

08:25 happens during this critical period of development Children and they have repeated infections they

08:31 hear in one year. And then imperative that you have the tubes placed

08:38 to prevent the infections and to improve hearing. It's not only just the

08:43 itself, it's also the learning that from the hearing too. Did you

08:47 a question? Sorry. Um So look at the structure if you're from

08:54 there, would you be able to draw ears? Here's what you hear

09:00 wasn't there? Could we breathe through ears? Okay. I don't

09:08 Nobody has uh asked that question uh you break their drum. But I

09:17 wish that to anybody to happen. may feel windy and win here but

09:24 don't know. I don't know. Probably not very efficient because we don't

09:32 have a mechanism of inhaling anything from from the air. So like a

09:37 . And you know that moves the and houses. But the reference my

09:46 sure. Because it's also somehow linked the sinuses too. So it's all

09:55 . It's linked to the sinus pressure . So when you're talking about me

09:59 not be the ear pressure, but could be uh sinuses actually at some

10:05 it went away but for about 23 I had tremendous pain going up and

10:11 like really bad for like 5 10 . I thought my head would

10:15 I couldn't equalize the pressure. And was something going on with my

10:19 And my nose was kind of a too at the time. Then it

10:23 away eventually. Which is interesting. So that's your station tubes. The

10:31 that you find here are the smallest in your body. Well, Mallia

10:38 and stay peas. And the foot plate of steps moves over the

10:45 . So now you have these traveling of air that they moved the

10:52 It's a mechanical movement of the The movement of the air starts moving

10:57 membrane. Air drum membrane. The of the air number of the air

11:02 starts moving the three obstacles. 123 more pork. So they amplify this

11:08 and they start moving the oval window the cochlear and the fluid in the

11:14 . Cochlear has a three chamber So if you take and cut the

11:21 cross sectional you will have scalar the on top. This is to the

11:25 apparatus. Callens media in the middle scala tympani at the bottom and scala

11:34 stimulus and scalar media. Yeah we'll about this in the second scallop a

11:43 A and scallop uh scalable stimulus scalar have paralympic and scala media has a

11:52 fluid called pendulum. Will come back it in the next slide. But

11:56 you have this organ of corti here haven't ethereal cell wall history of muscularity

12:03 the organ of corti. And this of corti will contain the hair

12:07 So these are the receptors that will transducer. This movement. Uh Air

12:16 and movement of the fluids into an reaction. Um This is coakley a

12:26 . If you take that snail and unwrap it straighten it out here here

12:33 will see that this is the oval that gets moved and here you have

12:39 skeleton. Funny at the bottom and very top with the very end of

12:45 very tip of the coakley is referred as apex. Okay so this is

12:51 the co crea would look like And we'll look at some of the

12:55 of the hair cells and what are hair south most responsive to. But

13:01 of the things that I mentioned here attenuation reflex. What do you do

13:06 you hear really loud sound? You your ears. What if your hands

13:12 tied? Oh you turn your head . What else do you do?

13:21 he's showing this. But also you this you start coming like squinting,

13:28 do that? And you'll see that hearing and the pressure changes. Okay

13:33 tighten up the muscles that move the , you make the muscles rigid.

13:39 is a protective mechanism accumulation reflex. that loud sound, repeating, persistent

13:47 . And what if you're you know bags of groceries or something you know

13:52 some situation. So this is happening course is happening independently whether you have

13:57 hands covering or not. But this what happens with attenuation reverts to tighten

14:03 the muscles that control the obstacles and make the movement more rigid. So

14:09 a protective mechanism reflects of these are three chambers. The paralympic is found

14:17 the scala tympani and vestibular to the alef is found in the scala media

14:26 is very similar to cerebrospinal fluid that discussed earlier. It's low potassium and

14:31 sodium concentration and do learn from that is enriched with potassium very high potassium

14:39 , very low sodium concentration and there's potassium gradient is established by active transport

14:47 the story of vascular areas here that feeds this fluid with high potassium

14:54 And this is important because potassium then the most important ion for the photo

15:00 the for the hearing, for the cells to transform the sound an electrochemical

15:08 . When we talked about the retina said that retina has fallen by point

15:15 of the outside world. I have point in the retina that's looking on

15:19 last year, on the left pointing writing. A last year on the

15:24 , pointed in the right and straight the middle middle chair. Each chair

15:29 have a point in my recommend that by point written the topic map gets

15:35 into lateral particular nucleus and the founders the primary visual cortex is preserved.

15:40 by point in the cochlear we have tonal topic map. Total topic map

15:47 such that the closer you are to base versus the apex, the closer

15:54 are to the base this is the of the cochlear from which you unfurl

15:59 enroll the snail. And the apex the very end of the snail.

16:04 cells that are located close to the window are most responsive to high frequencies

16:10 sound, 20 kHz 1817 16 As you move away. 15 14

16:21 8 kilohertz. And as you move the very apex, the south there

16:26 most responsive to low frequency yourself. this is called the tonal topic

16:31 And the best analogy that I always and I haven't thought of anything better

16:37 a gym this ribbon. So when journalist is flaring the Ruben,

16:45 very close to the ribbon. The of that ribbon movement is high frequency

16:51 the further the longer the ribbon it flares away into the lower

16:57 And the reason why I use that is because the movement of the of

17:02 of this network is mechanical and it's a rare movements. So it's it's

17:08 good analogy to keep in mind. closer you are, the higher frequencies

17:14 proceed, how does the transaction So this is the stay piece moving

17:23 oval window, moving the fluids If you can see at the apex

17:30 . It's also called the helicopter. is another term for the apex,

17:34 rima. And what happens is you this organ of corti. This organ

17:40 course it has the basilar membrane. has the supporting cells. And those

17:47 cells are housing hair cells and the cells. There is one row of

17:52 hair cells and three rows of outer cells. And those hair cells have

17:58 , stereo psyllium. Little protrusions. those protrusions are connected to the territorial

18:06 . Tech tomb is the roof sectorial . The roof number. Okay,

18:12 how you the same terms. And will repeat through any of the neuro

18:17 as you look in different uh systems well. So the pictorial member.

18:24 if there is no movement, if is no sound. This basil a

18:28 in the sitting still in the But as soon as there is a

18:34 of sound coming into the movement of hospital's movement of this oval window sort

18:39 like a pump. Every time you're sort of a toilet pump pumping,

18:44 moving the water, moving the you're pushing the water as you're pushing

18:49 fluids. The parallel around you have displacement and displacement of the basilar

18:57 As the basilar membrane lifts up the cilia on the hair cells will bend

19:04 this direction which is to the okay as the stereo cilia moves to

19:11 right you get deep polarization in the cells, it goes back to the

19:17 state position, the sound goes into . And as the basilar membrane gets

19:24 low below this line here you have stereo suited bending in the opposite direction

19:33 the left. And as the area's bend to the opposite direction you get

19:38 hyper polarization. These are receptor There is no action potential here,

19:45 like with photo receptors they d polarized hyper polarized, there was no action

19:51 . So these cells now take the pressure waves which is the traveling waves

19:58 sound pressure and converted into an electrical that are deep polarizing and hyper

20:09 So dense where there's a lot of . Deep polarization. Rare faction you

20:16 have hyper polarization. Okay so this terry movement or this wave mechanical wave

20:25 an electrical oscillation and obviously a wave activity that travels from the hair cells

20:32 the central surface we're hearing. This the organ of corti the surrounding the

20:40 south. There are three rows of hair cells, one row of inner

20:45 cells. And there is no axons the hair cells are sending up.

20:51 they get contacted by the spiral Know your rights. Okay. These

20:56 spiral ganglion cells to have their peripheral on going into the hair cells.

21:04 so mazar here and they formed the or the auditory It says auditory

21:11 It's the auditory component of the cochlear of cranial nerve. A vestibular cochlear

21:16 Russia. Huh? This is the and numbers the spiral ganglion cells going

21:23 into the brain. Stone. Cranial or brain stuff. So we'll look

21:28 the sparkling, You have these protrusions . You see the stereo cilia protruding

21:35 the pictorial number at the outer hair and the inner hair cells and you

21:40 see how fragile this is electro micrografx of how fragile these structures are.

21:48 what happens if you damage yourselves? no regeneration of yourself. There's no

21:55 of photo receptors there's no regeneration in CNN Yeah. So if you damaged

22:02 cells, if you have a partial of hearing. Does that hearing come

22:09 ? If you put glasses on or in. Does that mean two years

22:14 you don't need glasses anymore. It's opposite. It's usually two or five

22:19 later you need a stronger prescription for glasses because it just doesn't once the

22:25 has stretched out or you start losing of the system like here it doesn't

22:30 . And so now this membrane can an attached this pictorial membrane because the

22:36 underneath could be dead. Well, have lost the stereo cilia loose sectorial

22:42 and will result in ear ringing. discuss that very slide. Last slide

22:48 in this election today we talked about educated ion channels. This is action

22:57 . Both is going to potassium. was going to sodium channels. We

23:01 about Ligon gators receptor channels, chemicals them little late bindings. These are

23:13 gated channels and these are mechanically gated channels, potassium permeable channels but they're

23:20 T. R. P. One Which stands for transient receptor potential

23:26 channel is a mechanically gated channels. means that mechanical displacement in this case

23:34 displacement is the movement of the cilia regard to the pictorial membrane. It's

23:41 mechanical displacement that will open up this and because and a lamp is high

23:50 of potassium is potassium that is going rush into the air South Beach.

23:56 we always wanted sodium d polarizing because was a lot of sodium on the

24:02 now in and um emphasis special situations an influx of potassium causes deep polarization

24:08 the hair cells which opens up and voltage gated calcium channels. And with

24:15 opening of voltage gated calcium channels, is necessary for vesicular fusion and glutamate

24:23 excited terry neurotransmitter release here in the sounds. Yeah. Oh so this

24:31 again you can get to that voltage council channel in vesicles release and this

24:38 cause deep polarization and hyper polarization. channels are open. Deep polarization

24:45 There's going to be deep polarization in hair cell channels are closed is going

24:50 be hyper polarization. So once you the cilia, those mechanically gated trip

24:57 one channels will open, allow or of potassium whether they're interesting structurally

25:04 And the stereo Sylvia is. The channels are connected with the protein shame

25:11 referred to as stippling. So the are interconnected with this temple in

25:17 And when one potassium channel opens It on a tip link and encourages the

25:24 potassium channel to open. And that has a tip link to other organ

25:29 . That potassium channel two. This protein dynamics here a little those tails

25:35 dimensional tales interconnecting them so you move in one direction you open potassium channels

25:43 links open more potassium channels you have of potassium deep polarization. You move

25:48 in the opposite direction. All of channels are closed. There's no deep

25:53 . There's no calcium. You get opposite you get hyper polarization. Okay

25:58 this is basically a mechanical movement and movement to one side, potassium

26:04 mechanical movement to the other side. deep polarization. Yes. Yes.

26:11 defensively. Okay. Yes because that influence how far away the basilar membrane

26:23 gonna get removed. Okay. Low , low vibrations of sound. Small

26:32 movement of the window. That means remember and it's just moving up and

26:35 the wall. But you can have same pitch but include increasing loudness or

26:43 . And this is gonna be the of the days remember? And now

26:48 depending on where it moves along here will exemplify that frequency. So very

26:58 question. Is that similar or that ? Uh The type of energy,

27:07 type of center is so perfect. for instance where I it's like energy

27:15 so therefore it's type of uh Yeah you're moving the cilia in two

27:32 Yeah. And the photo receptors I don't move. It's light on or

27:38 . So you mean like quantum energy ? Uh that's not physics. It's

27:54 complicated question. Well I mean right the energy that we're talking about is

27:59 vibrations of the sound. So I'm sure I haven't thought of other

28:07 Maybe you can help me think through next time. But yes. Okay

28:17 we have deep polarization movement. One . We have hyper polarization movement.

28:21 other direction when I have this homework , what is the equilibrium potential value

28:25 potassium? Remember? Nice equation. equation was e. Or an ion

28:33 rtz uh log out concentration of a russell's log and concentration of reliance and

28:42 we have here we have very high in the end of the lymph with

28:49 . So when I told you there these rules, here's the potassium equilibrium

28:54 . It's uncertain cells. And in cells you calculate a little bit of

28:59 value for potassium and you'll see that is different because the concentration on the

29:03 and insult is different. That's an statement here is you can see that

29:08 are three rows of outer hair cells one row of inner hair cells.

29:13 where is most of the information coming ? From where most of the spinal

29:19 auditor and nerve fibers connecting to their connecting to inner hair cells. So

29:25 hair cells are special. And how hair cells is special in a different

29:31 . How our outer hair cell Why would you want to have three

29:35 of outer hair cells? But then most of the information from in rehearsal

29:40 special because outer hair cells have these pro dance. Okay. These motor

29:48 embedded inside the numbering and these motor are sort of like springs. That

29:55 that when the displacement of the pictorial and happens the outer hair cells have

30:02 ability to stretch their membranes even further to amplify the displacement of tutorial number

30:11 hmm. So you stretch these motor . You have them uncle pressed or

30:17 compress them. And this un compression compression influences the more deep polarization or

30:24 hyper polarization. It's really the sound by outer hair cells, the auditory

30:38 , which has some similarities and differences visual pathway. And there's some interesting

30:45 here. So this is great exam for both labeling and concepts. But

30:50 have a spiral ganglion cell which is auditory neural fiber carrying that information into

30:56 ventral and dorsal cochlear nucleus. And way you read this diagram. That's

31:02 one. Here is a cut here mid brain through brain stem. Number

31:08 . Number two. Cut is Number three. Cut is in this

31:12 and it's located here. So this number one, this is number two

31:15 this is number three. So immediately the cochlear nuclei, the fibers crossed

31:23 . Some of them stay on the side and some of them cross over

31:27 the superior olive. So that means at the level of the superior.

31:32 of you already have by oral hearing by oral, from both ears.

31:40 from superior olive travels into the inferior include calculus is a part of corporate

31:47 gemini. And in theory calculus is the auditor information. The superior calculus

31:56 processing psychotic eye movements. Okay. the visual system, they're sitting there

32:02 this four structured corporate Yeah uh from Oculus that information projects into filaments into

32:14 medial j. Nicollet nucleus which is . Guess where it's located immediately to

32:20 lateral Janica significance and MGM or mediagenic nucleus is the sensory nucleus and the

32:28 was dedicated to auditor information processing and the MGM and the thalamus that information

32:37 into the primary auditory cortex. So what are some of the interesting

32:45 ? What are some of the similarities maybe we're seeing here? Of course

32:48 seeing similarities. Visual system engagement of . Islamic nucleus salama, cortical communication

32:54 visual system where we learned about critical communication. What is going on

33:00 First of all, inferior calculus talks satirical Oculus. Now your brain stem

33:06 do a lot if your brain stone the eyes doesn't have the columns or

33:11 cortex. What can your brain stuff ? Ask Corporate quadra gemenon. Now

33:18 has a hearing from both ears left right, satirical, ridiculous. Can

33:24 your eyes not surprising fast eye psychotic. I'm women may be tied

33:29 the sound coming from one direction or left right. You turn your eyes

33:35 . It influences so you have this behavior of moving the eyes and listening

33:40 the level of the brain stone. before the more advanced evolutionarily structures form

33:46 thalamus and cortex you already have the for the primitive animals of primitive primordial

33:54 or what not to move their eyes follow the sound from those directions just

33:59 here not having the rest of the here. Yeah, earlier like a

34:10 line is like what causes like dizziness nausea or something? Uh Well where

34:18 not sure there's many different things that cause dizziness and nausea. Um mm

34:27 I don't know if if you were cut the connection between insurance, very

34:36 Ulis. If it would cause dizziness nausea I think it may have caused

34:41 not be able to move your eyes respect to the sound and dizziness.

34:47 you mentioned business, the first thing come to me is the stimulus

34:50 So there's a lot of things there it's obviously tied to this to be

34:54 okay apparatus to. So there could a connection there. So it's a

34:59 question. I don't know if I a good answer to it.

35:03 the other statement here, brains them send feedback to the outer hair

35:10 Did we have feedback onto the Mhm. Both an auditory cortex talks

35:17 MGM and empirical Oculus. So if cortex can talk to MGM empirical wickedness

35:26 the brain stem can feed back onto hair cells. You have pretty much

35:31 central control of the amplification of But outer hair cells that makes

35:41 So you don't have central control of down the sound. But you can

35:47 out a hair sauce. Maybe you influencing how much they're moving or much

35:55 the polarized and so on. Cochlear are inputs all other arm by

36:01 So after this information comes into cochlear , that's it. It's present to

36:06 olive and it becomes by oral and is very different from the visual system

36:10 all the way to the primary Visual . In layer four we had ocular

36:15 columns that were responsive from inputs from one high that mom ocular information is

36:21 all the way through the cortex and mon oral it becomes actually viral very

36:27 at the level of the brain It's on the topic map.

36:34 briefly. Okay. To that end and see. Exactly. Yes.

36:43 a great question whether this could be of the ways that the central pathways

36:54 to the sound is unwanted or you off the sound and you actually um

37:03 like even sound like white noise sound puts it to sleep. So obviously

37:12 talking back to the periphery influences the . And if you're amplifying something that

37:19 you can tune into something more. if you dampen that amplification, that

37:24 that you could basically habituate or start certain frequencies of sound And maybe it

37:32 even happening subconsciously sometimes when you study music and it seems that the music

37:38 irritating you and then 15 minutes later notice that it's not irritating you

37:43 It's actually kind of helping you study . Uh again this is uh hopefully

37:55 answers your question. Yeah, you're . But there is a certain type

38:01 sound that you like the sound. kind of like it goes from

38:15 It's so I mean sound localization. have you ever been to an audio

38:23 room? You know what that is ? People spend hundreds of thousands of

38:29 like when you buy our ipod or and you spend 300 400 beats,

38:37 dollars you know, sounds that's all . It's all digitized. It's all

38:47 to certain frequencies. What's the real is analyzed life sounds, What's the

38:54 representation of analog sound records for It goes through to downplay the

39:03 Well then people will pay $100,000 for setup. And if you get an

39:08 you don't have to buy it, get an opportunity. There's some

39:12 there's one shop in Houston. I remember where this has been a

39:16 They sell high end. It's called five. I am high fidelity.

39:22 do you equipment High fidelity? Because is 1-1 representation and you want to

39:29 it as close to life music setting possible when you're listening to live

39:34 If you're in front of a five band or if you're in front of

39:38 know, 50 piece orchestra. When play they play on the left for

39:45 violence it when I'm there. Tympani in the back wind instruments here other

39:52 the instruments here. Fellas 2nd 3rd and you hear it all and of

39:57 when you see it it helps Oh the cello supplying there. So

40:03 focusing on that. Tympani is going the doctor focusing on that. So

40:09 point of high fidelity audio sound equipment not even the surround sound but from

40:18 speakers, the ability to reproduce the spatial arrangement of some you sit in

40:25 room. If it's a really high audio equipment, you will hear the

40:30 on the left with drums on the and the piano in the front.

40:35 will and that is that is really of how to reproduce that sound and

40:42 the spatial arrangement the same way that hear it. No. So let's

40:50 back to the more of a mundane here from from from the base to

40:57 apex. We have this total topic . High frequency cells that means the

41:03 cells have lived close to the base produce most of the deep polarization is

41:08 high frequency sound. The hair sauce live at the apex will react with

41:15 deep polarization. Czar mobilizations mostly to low frequencies and this tone, a

41:21 arrangement that deserved through the spiral ganglion that carry that information into the cochlear

41:27 . And then if you look in primary auditory cortex Instead of a visual

41:34 . Like it did the visual you actually have a frequency map.

41:38 the cells that live in this part the auditory cortex will produce action potentials

41:44 will respond to 500 hertz. The that live here 1000 hertz, living

41:50 8000 hertz. And cells that live 16,000 hertz. So there is a

41:56 a topic arrangement. It continues in primary auditory cortex. Now, how

42:04 we localize the sound? And we're good at localizing the sound. Um

42:11 we have the air structure and most the time you don't think of people's

42:17 unless they look funny when they're small the big or there's something you

42:23 but they're important, the outer ear the pennant because it captures the

42:30 So think about certain animals like Mhm. I have a dog and

42:37 ears can go back like this and can go up like this and can

42:42 sideways like this. Whoa ! We of do that. You know,

42:48 can cup our ear and try to better. We cannot just turn our

42:53 that way and hear the sound you know? So okay so we

42:58 have that ability. We don't have big years, you're sort of like

43:04 receiver channel if you think about elephants have huge ears. But the

43:10 that we have had this certain it's sort of like a sort of

43:16 a shell. It has certain it has certain mathematical arrangement that directs

43:23 sound that the angles into the auditory . So it gathers as much sound

43:30 this shape into driving it into the canal. The sound comes from the

43:35 that will hit you right here first then it will hit your left

43:40 Uh huh. You can see if sound is coming in the front.

43:44 milliseconds from the side, 0.3 milliseconds , layer 0.6. If the sound

43:51 coming from the right is going to the right ear and on the

43:54 you're going to have a sound And just because you have the sound

43:59 , you're going to be able to the sound on the right. But

44:02 the sound is coming from the front going to hit the ears at the

44:05 time. So that delay, whether hitting the left or the right

44:09 for both at the same time helps localize to where the sound is

44:14 And of course you will have the waves coming from different directions and you'll

44:18 the sound shadows and in different angles . But how does how do we

44:24 this on a on a circuit So this is the sound that's coming

44:30 this direction here, let's call it the left side initiates activity in the

44:35 nucleus. And that activity is sent the superior college. So the sound

44:39 from this side is just going to this year, let's say this year

44:43 half a millisecond to millisecond before the here. And that gives an opportunity

44:50 this cochlear nucleus processing information from this inform first neuron and Superior Olive traveled

44:59 the second neuron in superior Olive. when it reaches the third neuron and

45:04 Olive, that's when the sound now affected the opposite year and have generated

45:12 own action potential. And the two from the left in the right here

45:20 converge on your on three. If conversion neuron three, Superior Olive knows

45:29 is the code sounds from the If the sound came from the right

45:33 conversion neuron one spirituality will not sound from the right. If the sound

45:40 equally to both ears it would converge neuron to and you would know that

45:45 sound is either in front or behind . Yeah and this is the

45:50 So the slide millisecond delay of the being sent through the tunnel topic,

45:57 and through the interconnected circuit here. if it is on convergence on three

46:03 left, convergence on one is convergence in two is in front of

46:08 behind you and in fact we don't very good sound localization, We have

46:16 good sound localization but we don't have good of a sound localization as an

46:21 animals and I'll show you an example that. Imagine if you didn't have

46:28 vision and you had to find something the dark with sound that's very very

46:36 . But there are animal species that perfected that they don't use vision

46:41 So let's talk a little bit before get to that part, let's talk

46:45 the auditor disorders. Most of the impairments that you're seeing are conduction

46:53 So conduction impairments has anything to do mechanical infection in the air. A

47:00 of the eardrum calcifications of the Rupture of global and uh this is

47:09 mechanical and it impedes with the conduction sound conduction of that way. The

47:16 jump doesn't vote obstacles don't move it's not moving the low window

47:22 So it hasn't. The fact it affected the hair cells. And if

47:28 have sensory neuro damage that means that have loss of hearing and that means

47:34 you have neural damage. Tinnitus is most common sensory neural damage. It's

47:41 in the ears years, can ring you can hear it so I can

47:47 can I have tinnitus in my years I've had it for over 10 years

47:52 I don't think about it 95% of time. But when I do think

47:56 it, it's one of the most things because I hear my ears

48:00 How did that happen? I want concert and we met friends close by

48:05 speaker, didn't just feel the movement the subwoofer. It was Chaka Khan

48:12 in the microphone. You don't know unconscious from the 80s, really high

48:18 and I was standing, everybody is wrong with the sound. I went

48:22 , my ears were clogged, you how you come back and from a

48:25 concert sporting event or something like that your ears are like clogs for a

48:31 of hours. It's like ok one my ears are still clogged like there's

48:36 , you know, dampening when I hear, hey, I'm trying to

48:41 my nose, do everything. two days later, three days later

48:45 go through ideologist office, they checked here and I said yeah partial hearing

48:50 and you left here, you I deny it and I say this

48:54 just a bad test, results are going to be back in three weeks

48:58 it's gonna be okay you know? I come back in three weeks.

49:01 ideologist testament says sorry, a little of about 5-10%. Would you have

49:08 damage in the area on the left of high frequency sound? High frequency

49:14 , the pitch that I was listening Chaka khan screaming in my ear by

49:17 speakers at one time. So you I said I'm going to be back

49:23 year later and recover and no forget and they have ringing in my

49:29 So they tried to prescribe steroids. just increase the ringing in my

49:33 The steroids actually reduce the information following damage of the hair cells. But

49:38 increases the ringing in my ears. can stand it. So what has

49:42 ? I actually killed some of the cilia, Killed some of the hair

49:47 . And why is it drinking? those hair cells that are attached to

49:51 number and they're tightened their their trash you break them. What happens to

49:55 serial number and influence? So it's moving. It's constantly loose and that's

50:00 it is. It's constant loose movement these hair cells at a certain frequency

50:05 high frequency which gives me the ringing my ears. The way the company

50:10 built in, it's the way that twisted is that the human vocal range

50:16 hearing range of human voices is around band and it's usually typically preserved.

50:22 did they lose high frequency? It's closest to their drum. So it's

50:27 easiest also to lose. Okay, the further away you are or you're

50:32 that band with a human voices. get protection because you get protection from

50:38 movement of the membrane. The movement the fluid cochlear implants. And most

50:45 the things that you see with older especially, you know, instead of

50:50 you have hearing aids, the hearing is different from a cochlear implant.

50:55 aid is just amplifies the speaker It just listens to that same sound

51:01 just amplifies that sound. It's not implant. You put it in your

51:05 to take it out of their cochlear . The actual implants into the

51:12 And why would you do that? how would you do that? Obviously

51:17 you lost the hearing completely there's no cells. You cannot regenerate hair

51:24 you cannot even stimulate hair cells. left with stimulating spiral ganglion cells,

51:30 auditory nerve. And you're left with anatomy where the high frequencies processed here

51:37 low frequencies process of the apex. what happens is you actually take an

51:44 and you insert this electrode and wind around the coqui in the brain.

51:49 at different parts of this electrode you stimulating micro lectures that will stimulate spiral

51:56 cells. So you have now implant the skin and the receiver circuit that

52:04 the input. It processes there is sound processor that processes the input.

52:10 let's say now there is tim kilohertz coming. It processes 10 kHz sound

52:17 it sends it to 10 kHzertz Electrode is stimulating the part of the cochlear

52:25 responding to 10 kHzertz and tries to the frequencies of south. So once

52:32 have the hair cell loss you may ganglion cells still there because they are

52:37 affected by this movement, mechanical It's not a mechanical system. It's

52:42 electrochemical system and you could stimulate still spiral gang and the auditor in there

52:47 , partially bring back that that Okay, so let me uh pause

52:58 recording for a second. The last I want to show you is how

53:06 is the sound localization from eternal animals this very quick video Tuesday is the

53:13 landscape. The noise of wind and is filtered out. It's russell you

53:22 interested in. Mm hmm, false . But it doesn't have to wait

53:31 . Yeah. From deep under the . 11 transmits a high frequency Russell

53:38 around here for Russia, isn't Mm hmm. The 2nd 2 weeks

53:46 here. But this is the ultimate . It's it's like a satellite

53:55 The dish is formed by a ram feathers. We collect channel sound in

54:02 . Yeah. The eyes look central the vision actually forces for the

54:09 You see that this white things this white things are the ears and

54:20 us the ears are on the same plane. They're symmetrical and in these

54:27 they're a little bit off, one a little bit higher than the

54:32 So when we talked about the sound from the left and then to the

54:35 helps us it reaches the left first then the right. The same way

54:40 animals will have one year from the or the top reaching one here which

54:45 them this azimuth for this depth perception sound that we don't have making giving

54:52 the ability to hunt under snow, in the dark under snow. So

54:57 you're seeing here is shot in the . But they do the same in

55:00 dark, wow. Mhm. This united. I arranged with bristles giving

55:09 suddenly. It's like having a giant hand behind each ear. Mhm.

55:26 the point of your name. The to the receiver moved automatically. The

55:43 is not being too reckless. Standish And eyes are no focused from

55:52 point. Open all the way until landing. His experiments sorting begins.

56:02 old approach is absolutely silent. Oh development, edges that simply caressed the

56:17 . As a result you will interfere the transmission. Yeah. The head

56:29 forest of all things. Even if has to fly and obstacles. A

56:56 it's not just a single diet bomb . The head stays long time.

57:04 the talons are raised it in the of sound channel that extended to evolve

57:16 a little effort. Even if we compensate the harvard, it's like single

57:32 . The body twists and the certain position. You're dealing with

57:44 That shock and specialized physical defenses like and be useless. Mhm. So

57:51 concludes our auditory system and I think just a great example to know that

57:56 really sophisticated development for different animals depending what they have to do. We

58:02 to hunt it mind. All Have a great weekend. I'll see

58:05 all on Tuesday. I have a people that got six taking the

58:08 so release it next week. You any questions you can address then next

58:14 with me and I'll let you know the quiz next week too. Thanks

58:18 being here. I appreciate it. report. Yeah. Would

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