Cochlear Amplifier

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From the course by The University of Chicago

Understanding the Brain: The Neurobiology of Everyday Life

652 ratings

The University of Chicago

Understanding the Brain: The Neurobiology of Everyday Life

652 ratings

Learn how the nervous system produces behavior, how we use our brain every day, and how neuroscience can explain the common problems afflicting people today. We will study functional human neuroanatomy and neuronal communication, and then use this information to understand how we perceive the outside world, move our bodies voluntarily, stay alive, and play well with others.

From the lesson

Hearing

The sound of birds chirping in the morning, a babbling brook or crashing waves on the beach, or warm conversation with the ones you love. The experience of all these things requires the ability to hear. Arguably the most important sense for human communication, it is also the most commonly impaired of our senses. In this module, you will learn how the human ear is artfully designed to enhance our ability to hear the human voice. You will follow sound waves as they travel from the external world, to the eardrum, through the bones of the middle ear, and to the cochlea that transduces sound information into neural impulses.

Cochlear Amplifier3:21

Outer Hair Cell Motility6:12

Otoacoustic Emissions3:25

Hearing Loss7:08

Weber and Rinne7:33

Meet the Instructors

Peggy Mason
Professor
Neurobiology

[MUSIC]

Okay, so let's talk about the cochlear amplifier.

We're going to, first, describe, in this first segment,

we're going to describe what's the problem that the cochlear am, or

where are the problems that the cochlear amplifier solves, and there are two.

First of all, we, this shows, we're back to our,

our image where there, this is the, the breadth of this,

the height of this is proportional to the amplitude of the stimulus.

So the stimulus has grown in intensity in the external ear, but

we've lost intensity in the middle ear.

And then we would lose more oop,

it would be down here if nothing else happened.

The amount of sound coming into the, inner ear, would also be very, very small,

and, we would be, we would have very poor, sound detection.

So one problem is this amplification.

We, we need to boost up.

The second problem, if we come over to the board, relates to, the,

the effect of this auditory prism.

Now the, the prism that Buchesi found, it does a great job of

differentiating between ten thousand hertz and, and a thousand hertz.

It doesn't do a great job of discriminating between,

say, 500Hz and 502Hz.

But you, most of you, can tell the difference between 500 and 502.

You can make very fine judgments.

You can make discriminations between sounds that arrive here and here.

But vicase's prism is too gross, too coarse to allow for

these two to these two sounds to be discriminated.

And so the second problem the cochlear amplifier,

is going to help us with is to discriminate and make the tonotopy of

the cochlea even finer than it would be with just the,

the, just the prism that is, that,

that results from the physical structure.

So, cadavers have, are only able to use the prism component of

amplifying and we knew from a long time, for a long time.

We have known for a long time that, in fact,

there had to be something that amplified sounds even more and

that refined the, the frequency discrimination of sounds even more

that was present in living cochlea, but not present in dead cochlea.

And that came to be called, the cochlear amplifier.

So, the cochlear amplifier, the search was on.

And in the next segment we will find that cochlear amplifier.

[MUSIC]

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