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00:00 | So watch on the auditory system. I'm gonna start with that. What |
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00:09 | sound? I was like what are properties of life? But the properties |
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00:15 | sound hearing is neural perception of sound . Sound Is traveling waves for vibrations |
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00:26 | air molecules traveled 343 m A second 767 mph. So you can drive |
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00:34 | fast as the sound. But you fly faster than sound in the speed |
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00:38 | sound. And when the sound travels have these regions of compression and rear |
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00:47 | compress. Their molecules are rare fact they're molecules. And an example is |
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00:53 | you hit the fork and that fork vibrating the tuning fork the vibration of |
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00:58 | fork creates the vibration of the air . It spread from that for in |
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01:04 | forms of the compressed and we're a that weighs oscillations and and the movement |
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01:12 | the air molecules. Likewise when you the speaker producing the sound, the |
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01:19 | were producing the information from the phone from the record player. From the |
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01:25 | . D. Player. From the player and it's connected to speakers and |
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01:32 | have the star fragments. These membranes . So the faster they vibrate, |
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01:39 | higher pitch they represent the slower to . And the larger typically the |
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01:44 | This is a low range the subway sound low frequency range but this vibration |
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01:50 | the membrane even in your headphones there's little tiny speaker that vibrates a tiny |
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01:57 | and produces the sound for you And here And this is just compressed and |
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02:01 | affected waves of air that are Human audible range is 20-20 kHzertz When |
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02:10 | hurts 20 kHz. So these are times per second. sound oscillations up |
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02:16 | 20,000 times per second. Ultrasound is 20 kHz. A lot of marine |
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02:25 | . A lot of dolphin fish, communicated their high frequencies and can perceive |
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02:32 | high frequencies. We get them cut . You can sometimes perceive those very |
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02:37 | frequencies if they cross through the barrier water to the hall of the ship |
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02:43 | something like this, you can actually hear those high frequencies. But other |
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02:47 | that there's a whole world of communication the water very high frequencies that we |
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02:53 | not perceive. Infrasound below pointing hurts like our vibrations, sub warfare |
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03:01 | If you I think actually if you're a speaker, I mean buying a |
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03:06 | it will even say it goes down 10 birds. Why does it go |
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03:12 | to temper? You're not going to able to hear below 20 months. |
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03:18 | at 10 hertz and the subwoofer vibration the air movement, you're going to |
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03:24 | able to feel it. So you be able to perceive it through this |
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03:27 | of sensory system which is a different . And if any of you have |
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03:31 | to a music hall club concert. you stood close to the sub |
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03:37 | You actually feel the physical movement of molecules on your amount of sensor |
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03:42 | 19 years. So you have the and you have the loudness. This |
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03:50 | low frequencies. The pitch. High mm. Okay low intensity. It's |
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04:00 | same pitch but high intensity is the pitch louder. So that's what intensity |
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04:09 | loudness and frequency is pitched. Yeah have the structure in your here. |
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04:20 | have the outer area of the middle and the inner. Here these are |
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04:24 | major divisions and you have the owner the air. This is out of |
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04:32 | . And the auditory canal is also external auditory miatas that goes into the |
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04:38 | panic membrane symphony. Just the This is your ear drum that is |
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04:46 | to obstacles. So these are mechanical that move but the giants with each |
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04:53 | and move the over window. So obstacles from the drum is in the |
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04:58 | air. And then the cochlear which a part of the vestibular cochlear apparatus |
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05:04 | the oval window. Then is in inner. Here The vestibular cochlear apparatus |
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05:10 | the cranial nerve eight or the output uh from the tubular cokie apparatuses cranial |
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05:17 | eight which consists of the stimulus to and cochlear component. So cochlear component |
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05:27 | the one that is coming from the that looks sort of like a snail |
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05:33 | up snail in humans. It's about size of a pea like snoopy. |
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05:41 | uh Jenna external ear air wax would living here some panic membrane air |
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05:49 | And then in the inner middle ear have the pharynx uh descending interference. |
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05:56 | have the station too. This is station to station tube. It's used |
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06:03 | equalizing the pressure between your outside the and the inside of the mouth. |
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06:09 | when you're flying for example and you the elevation or if you're going down |
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06:15 | hill or up the hill when you feeling that most often what you start |
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06:20 | is opening your mouth may be Don't even knows and that equalizes |
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06:28 | If you don't equalize the pressure and ascend with an airplane you can actually |
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06:33 | pretty serious headache that forms uh And station tubes is also the side as |
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06:40 | can see. It's beautiful. It all the way from here into the |
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06:45 | of the throat and the banks. also the site where the infections are |
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06:50 | . In fact take place. It's great environment. It's really moist in |
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06:55 | back of the throat there. So lot of bacterial species. It's |
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07:00 | moist, protected. They established themselves . And when you hear somebody had |
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07:08 | tubes replaced and they hear that I my tubes or my child had the |
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07:14 | replaced. The station tubes get replaced the plastic insert tubes and plastic is |
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07:22 | a favorable environment for bacteria to But why would you do that. |
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07:28 | if you recall? We talked about and in particular we talked about critical |
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07:33 | of development and we look at an in visual system where one eye vision |
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07:40 | and one eye for six days permanently the cortex during this critical period of |
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07:47 | irreversibly. And uh I was no responsive and the cortex was no longer |
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07:54 | to the stimulus to that. I that example. So what happens if |
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08:01 | this critical period of development for especially our Children and publishes, they're learning |
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08:06 | they're listening to things? You deprive of hearing in one year. You |
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08:12 | restructure the circuits too and you ignore central pathways. Started ignoring the periphery |
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08:22 | is clogged up. It's no longer . It's not listening. So if |
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08:25 | happens during this critical period of development Children and they have repeated infections they |
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08:31 | hear in one year. And then imperative that you have the tubes placed |
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08:38 | to prevent the infections and to improve hearing. It's not only just the |
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08:43 | itself, it's also the learning that from the hearing too. Did you |
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08:47 | a question? Sorry. Um So look at the structure if you're from |
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08:54 | there, would you be able to draw ears? Here's what you hear |
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09:00 | wasn't there? Could we breathe through ears? Okay. I don't |
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09:08 | Nobody has uh asked that question uh you break their drum. But I |
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09:17 | wish that to anybody to happen. may feel windy and win here but |
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09:24 | don't know. I don't know. Probably not very efficient because we don't |
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09:32 | have a mechanism of inhaling anything from from the air. So like a |
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09:37 | . And you know that moves the and houses. But the reference my |
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09:46 | sure. Because it's also somehow linked the sinuses too. So it's all |
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09:55 | . It's linked to the sinus pressure . So when you're talking about me |
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09:59 | not be the ear pressure, but could be uh sinuses actually at some |
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10:05 | it went away but for about 23 I had tremendous pain going up and |
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10:11 | like really bad for like 5 10 . I thought my head would |
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10:15 | I couldn't equalize the pressure. And was something going on with my |
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10:19 | And my nose was kind of a too at the time. Then it |
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10:23 | away eventually. Which is interesting. So that's your station tubes. The |
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10:31 | that you find here are the smallest in your body. Well, Mallia |
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10:38 | and stay peas. And the foot plate of steps moves over the |
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10:45 | . So now you have these traveling of air that they moved the |
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10:52 | It's a mechanical movement of the The movement of the air starts moving |
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10:57 | membrane. Air drum membrane. The of the air number of the air |
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11:02 | starts moving the three obstacles. 123 more pork. So they amplify this |
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11:08 | and they start moving the oval window the cochlear and the fluid in the |
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11:14 | . Cochlear has a three chamber So if you take and cut the |
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11:21 | cross sectional you will have scalar the on top. This is to the |
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11:25 | apparatus. Callens media in the middle scala tympani at the bottom and scala |
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11:34 | stimulus and scalar media. Yeah we'll about this in the second scallop a |
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11:43 | A and scallop uh scalable stimulus scalar have paralympic and scala media has a |
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11:52 | fluid called pendulum. Will come back it in the next slide. But |
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11:56 | you have this organ of corti here haven't ethereal cell wall history of muscularity |
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12:03 | the organ of corti. And this of corti will contain the hair |
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12:07 | So these are the receptors that will transducer. This movement. Uh Air |
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12:16 | and movement of the fluids into an reaction. Um This is coakley a |
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12:26 | . If you take that snail and unwrap it straighten it out here here |
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12:33 | will see that this is the oval that gets moved and here you have |
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12:39 | skeleton. Funny at the bottom and very top with the very end of |
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12:45 | very tip of the coakley is referred as apex. Okay so this is |
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12:51 | the co crea would look like And we'll look at some of the |
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12:55 | of the hair cells and what are hair south most responsive to. But |
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13:01 | of the things that I mentioned here attenuation reflex. What do you do |
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13:06 | you hear really loud sound? You your ears. What if your hands |
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13:12 | tied? Oh you turn your head . What else do you do? |
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13:21 | he's showing this. But also you this you start coming like squinting, |
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13:28 | do that? And you'll see that hearing and the pressure changes. Okay |
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13:33 | tighten up the muscles that move the , you make the muscles rigid. |
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13:39 | is a protective mechanism accumulation reflex. that loud sound, repeating, persistent |
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13:47 | . And what if you're you know bags of groceries or something you know |
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13:52 | some situation. So this is happening course is happening independently whether you have |
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13:57 | hands covering or not. But this what happens with attenuation reverts to tighten |
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14:03 | the muscles that control the obstacles and make the movement more rigid. So |
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14:09 | a protective mechanism reflects of these are three chambers. The paralympic is found |
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14:17 | the scala tympani and vestibular to the alef is found in the scala media |
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14:26 | is very similar to cerebrospinal fluid that discussed earlier. It's low potassium and |
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14:31 | sodium concentration and do learn from that is enriched with potassium very high potassium |
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14:39 | , very low sodium concentration and there's potassium gradient is established by active transport |
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14:47 | the story of vascular areas here that feeds this fluid with high potassium |
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14:54 | And this is important because potassium then the most important ion for the photo |
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15:00 | the for the hearing, for the cells to transform the sound an electrochemical |
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15:08 | . When we talked about the retina said that retina has fallen by point |
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15:15 | of the outside world. I have point in the retina that's looking on |
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15:19 | last year, on the left pointing writing. A last year on the |
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15:24 | , pointed in the right and straight the middle middle chair. Each chair |
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15:29 | have a point in my recommend that by point written the topic map gets |
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15:35 | into lateral particular nucleus and the founders the primary visual cortex is preserved. |
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15:40 | by point in the cochlear we have tonal topic map. Total topic map |
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15:47 | such that the closer you are to base versus the apex, the closer |
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15:54 | are to the base this is the of the cochlear from which you unfurl |
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15:59 | enroll the snail. And the apex the very end of the snail. |
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16:04 | cells that are located close to the window are most responsive to high frequencies |
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16:10 | sound, 20 kHz 1817 16 As you move away. 15 14 |
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16:21 | 8 kilohertz. And as you move the very apex, the south there |
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16:26 | most responsive to low frequency yourself. this is called the tonal topic |
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16:31 | And the best analogy that I always and I haven't thought of anything better |
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16:37 | a gym this ribbon. So when journalist is flaring the Ruben, |
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16:45 | very close to the ribbon. The of that ribbon movement is high frequency |
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16:51 | the further the longer the ribbon it flares away into the lower |
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16:57 | And the reason why I use that is because the movement of the of |
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17:02 | of this network is mechanical and it's a rare movements. So it's it's |
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17:08 | good analogy to keep in mind. closer you are, the higher frequencies |
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17:14 | proceed, how does the transaction So this is the stay piece moving |
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17:23 | oval window, moving the fluids If you can see at the apex |
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17:30 | . It's also called the helicopter. is another term for the apex, |
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17:34 | rima. And what happens is you this organ of corti. This organ |
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17:40 | course it has the basilar membrane. has the supporting cells. And those |
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17:47 | cells are housing hair cells and the cells. There is one row of |
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17:52 | hair cells and three rows of outer cells. And those hair cells have |
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17:58 | , stereo psyllium. Little protrusions. those protrusions are connected to the territorial |
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18:06 | . Tech tomb is the roof sectorial . The roof number. Okay, |
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18:12 | how you the same terms. And will repeat through any of the neuro |
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18:17 | as you look in different uh systems well. So the pictorial member. |
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18:24 | if there is no movement, if is no sound. This basil a |
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18:28 | in the sitting still in the But as soon as there is a |
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18:34 | of sound coming into the movement of hospital's movement of this oval window sort |
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18:39 | like a pump. Every time you're sort of a toilet pump pumping, |
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18:44 | moving the water, moving the you're pushing the water as you're pushing |
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18:49 | fluids. The parallel around you have displacement and displacement of the basilar |
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18:57 | As the basilar membrane lifts up the cilia on the hair cells will bend |
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19:04 | this direction which is to the okay as the stereo cilia moves to |
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19:11 | right you get deep polarization in the cells, it goes back to the |
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19:17 | state position, the sound goes into . And as the basilar membrane gets |
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19:24 | low below this line here you have stereo suited bending in the opposite direction |
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19:33 | the left. And as the area's bend to the opposite direction you get |
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19:38 | hyper polarization. These are receptor There is no action potential here, |
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19:45 | like with photo receptors they d polarized hyper polarized, there was no action |
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19:51 | . So these cells now take the pressure waves which is the traveling waves |
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19:58 | sound pressure and converted into an electrical that are deep polarizing and hyper |
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20:09 | So dense where there's a lot of . Deep polarization. Rare faction you |
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20:16 | have hyper polarization. Okay so this terry movement or this wave mechanical wave |
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20:25 | an electrical oscillation and obviously a wave activity that travels from the hair cells |
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20:32 | the central surface we're hearing. This the organ of corti the surrounding the |
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20:40 | south. There are three rows of hair cells, one row of inner |
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20:45 | cells. And there is no axons the hair cells are sending up. |
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20:51 | they get contacted by the spiral Know your rights. Okay. These |
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20:56 | spiral ganglion cells to have their peripheral on going into the hair cells. |
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21:04 | so mazar here and they formed the or the auditory It says auditory |
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21:11 | It's the auditory component of the cochlear of cranial nerve. A vestibular cochlear |
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21:16 | Russia. Huh? This is the and numbers the spiral ganglion cells going |
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21:23 | into the brain. Stone. Cranial or brain stuff. So we'll look |
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21:28 | the sparkling, You have these protrusions . You see the stereo cilia protruding |
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21:35 | the pictorial number at the outer hair and the inner hair cells and you |
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21:40 | see how fragile this is electro micrografx of how fragile these structures are. |
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21:48 | what happens if you damage yourselves? no regeneration of yourself. There's no |
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21:55 | of photo receptors there's no regeneration in CNN Yeah. So if you damaged |
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22:02 | cells, if you have a partial of hearing. Does that hearing come |
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22:09 | ? If you put glasses on or in. Does that mean two years |
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22:14 | you don't need glasses anymore. It's opposite. It's usually two or five |
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22:19 | later you need a stronger prescription for glasses because it just doesn't once the |
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22:25 | has stretched out or you start losing of the system like here it doesn't |
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22:30 | . And so now this membrane can an attached this pictorial membrane because the |
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22:36 | underneath could be dead. Well, have lost the stereo cilia loose sectorial |
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22:42 | and will result in ear ringing. discuss that very slide. Last slide |
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22:48 | in this election today we talked about educated ion channels. This is action |
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22:57 | . Both is going to potassium. was going to sodium channels. We |
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23:01 | about Ligon gators receptor channels, chemicals them little late bindings. These are |
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23:13 | gated channels and these are mechanically gated channels, potassium permeable channels but they're |
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23:20 | T. R. P. One Which stands for transient receptor potential |
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23:26 | channel is a mechanically gated channels. means that mechanical displacement in this case |
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23:34 | displacement is the movement of the cilia regard to the pictorial membrane. It's |
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23:41 | mechanical displacement that will open up this and because and a lamp is high |
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23:50 | of potassium is potassium that is going rush into the air South Beach. |
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23:56 | we always wanted sodium d polarizing because was a lot of sodium on the |
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24:02 | now in and um emphasis special situations an influx of potassium causes deep polarization |
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24:08 | the hair cells which opens up and voltage gated calcium channels. And with |
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24:15 | opening of voltage gated calcium channels, is necessary for vesicular fusion and glutamate |
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24:23 | excited terry neurotransmitter release here in the sounds. Yeah. Oh so this |
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24:31 | again you can get to that voltage council channel in vesicles release and this |
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24:38 | cause deep polarization and hyper polarization. channels are open. Deep polarization |
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24:45 | There's going to be deep polarization in hair cell channels are closed is going |
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24:50 | be hyper polarization. So once you the cilia, those mechanically gated trip |
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24:57 | one channels will open, allow or of potassium whether they're interesting structurally |
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25:04 | And the stereo Sylvia is. The channels are connected with the protein shame |
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25:11 | referred to as stippling. So the are interconnected with this temple in |
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25:17 | And when one potassium channel opens It on a tip link and encourages the |
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25:24 | potassium channel to open. And that has a tip link to other organ |
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25:29 | . That potassium channel two. This protein dynamics here a little those tails |
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25:35 | dimensional tales interconnecting them so you move in one direction you open potassium channels |
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25:43 | links open more potassium channels you have of potassium deep polarization. You move |
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25:48 | in the opposite direction. All of channels are closed. There's no deep |
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25:53 | . There's no calcium. You get opposite you get hyper polarization. Okay |
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25:58 | this is basically a mechanical movement and movement to one side, potassium |
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26:04 | mechanical movement to the other side. deep polarization. Yes. Yes. |
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26:11 | defensively. Okay. Yes because that influence how far away the basilar membrane |
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26:23 | gonna get removed. Okay. Low , low vibrations of sound. Small |
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26:32 | movement of the window. That means remember and it's just moving up and |
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26:35 | the wall. But you can have same pitch but include increasing loudness or |
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26:43 | . And this is gonna be the of the days remember? And now |
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26:48 | depending on where it moves along here will exemplify that frequency. So very |
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26:58 | question. Is that similar or that ? Uh The type of energy, |
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27:07 | type of center is so perfect. for instance where I it's like energy |
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27:15 | so therefore it's type of uh Yeah you're moving the cilia in two |
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27:32 | Yeah. And the photo receptors I don't move. It's light on or |
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27:38 | . So you mean like quantum energy ? Uh that's not physics. It's |
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27:54 | complicated question. Well I mean right the energy that we're talking about is |
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27:59 | vibrations of the sound. So I'm sure I haven't thought of other |
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28:07 | Maybe you can help me think through next time. But yes. Okay |
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28:17 | we have deep polarization movement. One . We have hyper polarization movement. |
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28:21 | other direction when I have this homework , what is the equilibrium potential value |
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28:25 | potassium? Remember? Nice equation. equation was e. Or an ion |
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28:33 | rtz uh log out concentration of a russell's log and concentration of reliance and |
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28:42 | we have here we have very high in the end of the lymph with |
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28:49 | . So when I told you there these rules, here's the potassium equilibrium |
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28:54 | . It's uncertain cells. And in cells you calculate a little bit of |
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28:59 | value for potassium and you'll see that is different because the concentration on the |
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29:03 | and insult is different. That's an statement here is you can see that |
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29:08 | are three rows of outer hair cells one row of inner hair cells. |
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29:13 | where is most of the information coming ? From where most of the spinal |
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29:19 | auditor and nerve fibers connecting to their connecting to inner hair cells. So |
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29:25 | hair cells are special. And how hair cells is special in a different |
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29:31 | . How our outer hair cell Why would you want to have three |
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29:35 | of outer hair cells? But then most of the information from in rehearsal |
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29:40 | special because outer hair cells have these pro dance. Okay. These motor |
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29:48 | embedded inside the numbering and these motor are sort of like springs. That |
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29:55 | that when the displacement of the pictorial and happens the outer hair cells have |
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30:02 | ability to stretch their membranes even further to amplify the displacement of tutorial number |
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30:11 | hmm. So you stretch these motor . You have them uncle pressed or |
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30:17 | compress them. And this un compression compression influences the more deep polarization or |
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30:24 | hyper polarization. It's really the sound by outer hair cells, the auditory |
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30:38 | , which has some similarities and differences visual pathway. And there's some interesting |
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30:45 | here. So this is great exam for both labeling and concepts. But |
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30:50 | have a spiral ganglion cell which is auditory neural fiber carrying that information into |
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30:56 | ventral and dorsal cochlear nucleus. And way you read this diagram. That's |
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31:02 | one. Here is a cut here mid brain through brain stem. Number |
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31:08 | . Number two. Cut is Number three. Cut is in this |
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31:12 | and it's located here. So this number one, this is number two |
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31:15 | this is number three. So immediately the cochlear nuclei, the fibers crossed |
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31:23 | . Some of them stay on the side and some of them cross over |
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31:27 | the superior olive. So that means at the level of the superior. |
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31:32 | of you already have by oral hearing by oral, from both ears. |
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31:40 | from superior olive travels into the inferior include calculus is a part of corporate |
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31:47 | gemini. And in theory calculus is the auditor information. The superior calculus |
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31:56 | processing psychotic eye movements. Okay. the visual system, they're sitting there |
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32:02 | this four structured corporate Yeah uh from Oculus that information projects into filaments into |
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32:14 | medial j. Nicollet nucleus which is . Guess where it's located immediately to |
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32:20 | lateral Janica significance and MGM or mediagenic nucleus is the sensory nucleus and the |
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32:28 | was dedicated to auditor information processing and the MGM and the thalamus that information |
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32:37 | into the primary auditory cortex. So what are some of the interesting |
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32:45 | ? What are some of the similarities maybe we're seeing here? Of course |
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32:48 | seeing similarities. Visual system engagement of . Islamic nucleus salama, cortical communication |
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32:54 | visual system where we learned about critical communication. What is going on |
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33:00 | First of all, inferior calculus talks satirical Oculus. Now your brain stem |
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33:06 | do a lot if your brain stone the eyes doesn't have the columns or |
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33:11 | cortex. What can your brain stuff ? Ask Corporate quadra gemenon. Now |
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33:18 | has a hearing from both ears left right, satirical, ridiculous. Can |
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33:24 | your eyes not surprising fast eye psychotic. I'm women may be tied |
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33:29 | the sound coming from one direction or left right. You turn your eyes |
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33:35 | . It influences so you have this behavior of moving the eyes and listening |
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33:40 | the level of the brain stone. before the more advanced evolutionarily structures form |
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33:46 | thalamus and cortex you already have the for the primitive animals of primitive primordial |
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33:54 | or what not to move their eyes follow the sound from those directions just |
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33:59 | here not having the rest of the here. Yeah, earlier like a |
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34:10 | line is like what causes like dizziness nausea or something? Uh Well where |
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34:18 | not sure there's many different things that cause dizziness and nausea. Um mm |
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34:27 | I don't know if if you were cut the connection between insurance, very |
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34:36 | Ulis. If it would cause dizziness nausea I think it may have caused |
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34:41 | not be able to move your eyes respect to the sound and dizziness. |
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34:47 | you mentioned business, the first thing come to me is the stimulus |
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34:50 | So there's a lot of things there it's obviously tied to this to be |
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34:54 | okay apparatus to. So there could a connection there. So it's a |
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34:59 | question. I don't know if I a good answer to it. |
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35:03 | the other statement here, brains them send feedback to the outer hair |
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35:10 | Did we have feedback onto the Mhm. Both an auditory cortex talks |
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35:17 | MGM and empirical Oculus. So if cortex can talk to MGM empirical wickedness |
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35:26 | the brain stem can feed back onto hair cells. You have pretty much |
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35:31 | central control of the amplification of But outer hair cells that makes |
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35:41 | So you don't have central control of down the sound. But you can |
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35:47 | out a hair sauce. Maybe you influencing how much they're moving or much |
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35:55 | the polarized and so on. Cochlear are inputs all other arm by |
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36:01 | So after this information comes into cochlear , that's it. It's present to |
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36:06 | olive and it becomes by oral and is very different from the visual system |
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36:10 | all the way to the primary Visual . In layer four we had ocular |
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36:15 | columns that were responsive from inputs from one high that mom ocular information is |
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36:21 | all the way through the cortex and mon oral it becomes actually viral very |
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36:27 | at the level of the brain It's on the topic map. |
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36:34 | briefly. Okay. To that end and see. Exactly. Yes. |
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36:43 | a great question whether this could be of the ways that the central pathways |
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36:54 | to the sound is unwanted or you off the sound and you actually um |
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37:03 | like even sound like white noise sound puts it to sleep. So obviously |
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37:12 | talking back to the periphery influences the . And if you're amplifying something that |
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37:19 | you can tune into something more. if you dampen that amplification, that |
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37:24 | that you could basically habituate or start certain frequencies of sound And maybe it |
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37:32 | even happening subconsciously sometimes when you study music and it seems that the music |
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37:38 | irritating you and then 15 minutes later notice that it's not irritating you |
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37:43 | It's actually kind of helping you study . Uh again this is uh hopefully |
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37:55 | answers your question. Yeah, you're . But there is a certain type |
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38:01 | sound that you like the sound. kind of like it goes from |
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38:15 | It's so I mean sound localization. have you ever been to an audio |
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38:23 | room? You know what that is ? People spend hundreds of thousands of |
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38:29 | like when you buy our ipod or and you spend 300 400 beats, |
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38:37 | dollars you know, sounds that's all . It's all digitized. It's all |
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38:47 | to certain frequencies. What's the real is analyzed life sounds, What's the |
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38:54 | representation of analog sound records for It goes through to downplay the |
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39:03 | Well then people will pay $100,000 for setup. And if you get an |
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39:08 | you don't have to buy it, get an opportunity. There's some |
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39:12 | there's one shop in Houston. I remember where this has been a |
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39:16 | They sell high end. It's called five. I am high fidelity. |
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39:22 | do you equipment High fidelity? Because is 1-1 representation and you want to |
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39:29 | it as close to life music setting possible when you're listening to live |
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39:34 | If you're in front of a five band or if you're in front of |
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39:38 | know, 50 piece orchestra. When play they play on the left for |
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39:45 | violence it when I'm there. Tympani in the back wind instruments here other |
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39:52 | the instruments here. Fellas 2nd 3rd and you hear it all and of |
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39:57 | when you see it it helps Oh the cello supplying there. So |
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40:03 | focusing on that. Tympani is going the doctor focusing on that. So |
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40:09 | point of high fidelity audio sound equipment not even the surround sound but from |
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40:18 | speakers, the ability to reproduce the spatial arrangement of some you sit in |
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40:25 | room. If it's a really high audio equipment, you will hear the |
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40:30 | on the left with drums on the and the piano in the front. |
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40:35 | will and that is that is really of how to reproduce that sound and |
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40:42 | the spatial arrangement the same way that hear it. No. So let's |
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40:50 | back to the more of a mundane here from from from the base to |
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40:57 | apex. We have this total topic . High frequency cells that means the |
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41:03 | cells have lived close to the base produce most of the deep polarization is |
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41:08 | high frequency sound. The hair sauce live at the apex will react with |
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41:15 | deep polarization. Czar mobilizations mostly to low frequencies and this tone, a |
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41:21 | arrangement that deserved through the spiral ganglion that carry that information into the cochlear |
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41:27 | . And then if you look in primary auditory cortex Instead of a visual |
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41:34 | . Like it did the visual you actually have a frequency map. |
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41:38 | the cells that live in this part the auditory cortex will produce action potentials |
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41:44 | will respond to 500 hertz. The that live here 1000 hertz, living |
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41:50 | 8000 hertz. And cells that live 16,000 hertz. So there is a |
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41:56 | a topic arrangement. It continues in primary auditory cortex. Now, how |
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42:04 | we localize the sound? And we're good at localizing the sound. Um |
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42:11 | we have the air structure and most the time you don't think of people's |
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42:17 | unless they look funny when they're small the big or there's something you |
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42:23 | but they're important, the outer ear the pennant because it captures the |
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42:30 | So think about certain animals like Mhm. I have a dog and |
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42:37 | ears can go back like this and can go up like this and can |
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42:42 | sideways like this. Whoa ! We of do that. You know, |
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42:48 | can cup our ear and try to better. We cannot just turn our |
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42:53 | that way and hear the sound you know? So okay so we |
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42:58 | have that ability. We don't have big years, you're sort of like |
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43:04 | receiver channel if you think about elephants have huge ears. But the |
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43:10 | that we have had this certain it's sort of like a sort of |
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43:16 | a shell. It has certain it has certain mathematical arrangement that directs |
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43:23 | sound that the angles into the auditory . So it gathers as much sound |
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43:30 | this shape into driving it into the canal. The sound comes from the |
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43:35 | that will hit you right here first then it will hit your left |
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43:40 | Uh huh. You can see if sound is coming in the front. |
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43:44 | milliseconds from the side, 0.3 milliseconds , layer 0.6. If the sound |
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43:51 | coming from the right is going to the right ear and on the |
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43:54 | you're going to have a sound And just because you have the sound |
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43:59 | , you're going to be able to the sound on the right. But |
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44:02 | the sound is coming from the front going to hit the ears at the |
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44:05 | time. So that delay, whether hitting the left or the right |
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44:09 | for both at the same time helps localize to where the sound is |
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44:14 | And of course you will have the waves coming from different directions and you'll |
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44:18 | the sound shadows and in different angles . But how does how do we |
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44:24 | this on a on a circuit So this is the sound that's coming |
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44:30 | this direction here, let's call it the left side initiates activity in the |
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44:35 | nucleus. And that activity is sent the superior college. So the sound |
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44:39 | from this side is just going to this year, let's say this year |
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44:43 | half a millisecond to millisecond before the here. And that gives an opportunity |
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44:50 | this cochlear nucleus processing information from this inform first neuron and Superior Olive traveled |
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44:59 | the second neuron in superior Olive. when it reaches the third neuron and |
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45:04 | Olive, that's when the sound now affected the opposite year and have generated |
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45:12 | own action potential. And the two from the left in the right here |
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45:20 | converge on your on three. If conversion neuron three, Superior Olive knows |
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45:29 | is the code sounds from the If the sound came from the right |
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45:33 | conversion neuron one spirituality will not sound from the right. If the sound |
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45:40 | equally to both ears it would converge neuron to and you would know that |
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45:45 | sound is either in front or behind . Yeah and this is the |
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45:50 | So the slide millisecond delay of the being sent through the tunnel topic, |
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45:57 | and through the interconnected circuit here. if it is on convergence on three |
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46:03 | left, convergence on one is convergence in two is in front of |
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46:08 | behind you and in fact we don't very good sound localization, We have |
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46:16 | good sound localization but we don't have good of a sound localization as an |
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46:21 | animals and I'll show you an example that. Imagine if you didn't have |
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46:28 | vision and you had to find something the dark with sound that's very very |
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46:36 | . But there are animal species that perfected that they don't use vision |
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46:41 | So let's talk a little bit before get to that part, let's talk |
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46:45 | the auditor disorders. Most of the impairments that you're seeing are conduction |
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46:53 | So conduction impairments has anything to do mechanical infection in the air. A |
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47:00 | of the eardrum calcifications of the Rupture of global and uh this is |
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47:09 | mechanical and it impedes with the conduction sound conduction of that way. The |
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47:16 | jump doesn't vote obstacles don't move it's not moving the low window |
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47:22 | So it hasn't. The fact it affected the hair cells. And if |
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47:28 | have sensory neuro damage that means that have loss of hearing and that means |
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47:34 | you have neural damage. Tinnitus is most common sensory neural damage. It's |
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47:41 | in the ears years, can ring you can hear it so I can |
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47:47 | can I have tinnitus in my years I've had it for over 10 years |
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47:52 | I don't think about it 95% of time. But when I do think |
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47:56 | it, it's one of the most things because I hear my ears |
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48:00 | How did that happen? I want concert and we met friends close by |
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48:05 | speaker, didn't just feel the movement the subwoofer. It was Chaka Khan |
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48:12 | in the microphone. You don't know unconscious from the 80s, really high |
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48:18 | and I was standing, everybody is wrong with the sound. I went |
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48:22 | , my ears were clogged, you how you come back and from a |
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48:25 | concert sporting event or something like that your ears are like clogs for a |
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48:31 | of hours. It's like ok one my ears are still clogged like there's |
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48:36 | , you know, dampening when I hear, hey, I'm trying to |
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48:41 | my nose, do everything. two days later, three days later |
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48:45 | go through ideologist office, they checked here and I said yeah partial hearing |
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48:50 | and you left here, you I deny it and I say this |
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48:54 | just a bad test, results are going to be back in three weeks |
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48:58 | it's gonna be okay you know? I come back in three weeks. |
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49:01 | ideologist testament says sorry, a little of about 5-10%. Would you have |
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49:08 | damage in the area on the left of high frequency sound? High frequency |
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49:14 | , the pitch that I was listening Chaka khan screaming in my ear by |
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49:17 | speakers at one time. So you I said I'm going to be back |
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49:23 | year later and recover and no forget and they have ringing in my |
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49:29 | So they tried to prescribe steroids. just increase the ringing in my |
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49:33 | The steroids actually reduce the information following damage of the hair cells. But |
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49:38 | increases the ringing in my ears. can stand it. So what has |
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49:42 | ? I actually killed some of the cilia, Killed some of the hair |
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49:47 | . And why is it drinking? those hair cells that are attached to |
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49:51 | number and they're tightened their their trash you break them. What happens to |
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49:55 | serial number and influence? So it's moving. It's constantly loose and that's |
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50:00 | it is. It's constant loose movement these hair cells at a certain frequency |
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50:05 | high frequency which gives me the ringing my ears. The way the company |
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50:10 | built in, it's the way that twisted is that the human vocal range |
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50:16 | hearing range of human voices is around band and it's usually typically preserved. |
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50:22 | did they lose high frequency? It's closest to their drum. So it's |
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50:27 | easiest also to lose. Okay, the further away you are or you're |
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50:32 | that band with a human voices. get protection because you get protection from |
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50:38 | movement of the membrane. The movement the fluid cochlear implants. And most |
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50:45 | the things that you see with older especially, you know, instead of |
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50:50 | you have hearing aids, the hearing is different from a cochlear implant. |
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50:55 | aid is just amplifies the speaker It just listens to that same sound |
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51:01 | just amplifies that sound. It's not implant. You put it in your |
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51:05 | to take it out of their cochlear . The actual implants into the |
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51:12 | And why would you do that? how would you do that? Obviously |
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51:17 | you lost the hearing completely there's no cells. You cannot regenerate hair |
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51:24 | you cannot even stimulate hair cells. left with stimulating spiral ganglion cells, |
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51:30 | auditory nerve. And you're left with anatomy where the high frequencies processed here |
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51:37 | low frequencies process of the apex. what happens is you actually take an |
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51:44 | and you insert this electrode and wind around the coqui in the brain. |
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51:49 | at different parts of this electrode you stimulating micro lectures that will stimulate spiral |
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51:56 | cells. So you have now implant the skin and the receiver circuit that |
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52:04 | the input. It processes there is sound processor that processes the input. |
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52:10 | let's say now there is tim kilohertz coming. It processes 10 kHz sound |
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52:17 | it sends it to 10 kHzertz Electrode is stimulating the part of the cochlear |
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52:25 | responding to 10 kHzertz and tries to the frequencies of south. So once |
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52:32 | have the hair cell loss you may ganglion cells still there because they are |
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52:37 | affected by this movement, mechanical It's not a mechanical system. It's |
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52:42 | electrochemical system and you could stimulate still spiral gang and the auditor in there |
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52:47 | , partially bring back that that Okay, so let me uh pause |
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52:58 | recording for a second. The last I want to show you is how |
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53:06 | is the sound localization from eternal animals this very quick video Tuesday is the |
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53:13 | landscape. The noise of wind and is filtered out. It's russell you |
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53:22 | interested in. Mm hmm, false . But it doesn't have to wait |
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53:31 | . Yeah. From deep under the . 11 transmits a high frequency Russell |
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53:38 | around here for Russia, isn't Mm hmm. The 2nd 2 weeks |
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53:46 | here. But this is the ultimate . It's it's like a satellite |
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53:55 | The dish is formed by a ram feathers. We collect channel sound in |
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54:02 | . Yeah. The eyes look central the vision actually forces for the |
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54:09 | You see that this white things this white things are the ears and |
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54:20 | us the ears are on the same plane. They're symmetrical and in these |
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54:27 | they're a little bit off, one a little bit higher than the |
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54:32 | So when we talked about the sound from the left and then to the |
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54:35 | helps us it reaches the left first then the right. The same way |
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54:40 | animals will have one year from the or the top reaching one here which |
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54:45 | them this azimuth for this depth perception sound that we don't have making giving |
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54:52 | the ability to hunt under snow, in the dark under snow. So |
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54:57 | you're seeing here is shot in the . But they do the same in |
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55:00 | dark, wow. Mhm. This united. I arranged with bristles giving |
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55:09 | suddenly. It's like having a giant hand behind each ear. Mhm. |
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55:26 | the point of your name. The to the receiver moved automatically. The |
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55:43 | is not being too reckless. Standish And eyes are no focused from |
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55:52 | point. Open all the way until landing. His experiments sorting begins. |
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56:02 | old approach is absolutely silent. Oh development, edges that simply caressed the |
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56:17 | . As a result you will interfere the transmission. Yeah. The head |
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56:29 | forest of all things. Even if has to fly and obstacles. A |
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56:56 | it's not just a single diet bomb . The head stays long time. |
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57:04 | the talons are raised it in the of sound channel that extended to evolve |
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57:16 | a little effort. Even if we compensate the harvard, it's like single |
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57:32 | . The body twists and the certain position. You're dealing with |
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57:44 | That shock and specialized physical defenses like and be useless. Mhm. So |
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57:51 | concludes our auditory system and I think just a great example to know that |
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57:56 | really sophisticated development for different animals depending what they have to do. We |
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58:02 | to hunt it mind. All Have a great weekend. I'll see |
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58:05 | all on Tuesday. I have a people that got six taking the |
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58:08 | so release it next week. You any questions you can address then next |
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58:14 | with me and I'll let you know the quiz next week too. Thanks |
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58:18 | being here. I appreciate it. report. Yeah. Would |
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