00:01
So a cochlear implant is a small, complex electronic device that can help provide a sense of sound to a person whose profoundly deaf are severely hard of hearing.
00:11
Cochlear implants bypass damage portion of the ear and directly stimulate the auditory nerve.
00:17
An array of electrodes will be surgically implanted into the cochlea, which stimulate the auditory nerves in the cochlear.
00:26
You were asked to design an array of electrodes that will be implanted in the cochlea.
00:31
Please answer the following questions.
00:35
So the first is when designing a cochlear implant, you will use a number of electrodes that activate auditory neurons in the cochlea.
00:42
And you have five types of electrodes that respond to different frequencies.
00:46
So 8 ,000, 4 ,000, 2 ,000, and 1 ,000 hertz, and then finally 500 hertz.
00:53
So highest frequency is, excuse me, 8 ,000, lowest frequency is 500.
00:59
In the figure to the left, where would you place the five electrodes? please write down the frequencies from a to e.
01:08
Okay, so here is a, b, c, d, and then e is over here.
01:14
It's hard to see by the apex.
01:19
So remember in the terms of frequency is it's essentially how many waves per unit of time.
01:26
So high frequency like 8 ,000, oops, we would see sound waves something like this versus low frequency, much larger distance between the waves.
01:43
And so if we take this cochlea, which is a coil and we uncoil it, we have something like this with the membrane in the middle.
01:57
This is the base and this is the apex.
02:02
So when ours, a is by the base and e is by the apex.
02:09
So lower frequency or larger distance between the waves will be detected closer to the apex, whereas higher frequency will be detected by the base.
02:23
So again, think about how many waves per second, high frequency, there's lots of waves.
02:29
Those are detected earlier, right? when we've got lots of waves here versus low frequency that come in and have these bigger gaps between their waves because we need the waves to hit this membrane in order to be detected...