MCAT Question: How does the ear detect different Frequencies?

[coda4451]

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After sound in the air gets converted into vibrations in the fluid of the inner ear, this vibration travels along the scala vestibuli to the apex of the cochlea and then back down along the scala tympani to the base of the cochlea where the round window is. I understand that different regions of the cochlea detect different frequency. But I am confused about which part of the cochlea detects the different frequencies.
Is it that only vibrations traveling through fluid in the scala tympani get detected for frequency and not those traveling through fluid in the scala vestibuli because the basilar membrane of the organ of corti is on the scala tympani side of the cochlea? Is this correct or does vibrations in the scala vestibuli get detected for frequency too?

 

[kcehreuhcs]

Are you familiar with the concept of the traveling wave? Basically, what it means is that it's always the hair cells along the way that perceive the information, but the location of the waves amplitudes heavily depend on their frequencies.

Check out this:
https://en.wikipedia.org/wiki/Basilar_membrane
http://media-2.web.britannica.com/e...-004-99934987.jpg.pagespeed.ic.biPjhFI8uH.jpg

 

[Necr0sis713]

Don't sweat the small details. The key thing to remember is that high frequencies vibrate the hairs closest to the oval window, and lower frequencies the farthest.

But if you want to know the details: The sound waves get "funneled" in by the outer ear, go into the middle ear. Then, in the middle ear the malleus, incus, stapes vibrate the oval window. This vibration causes fluid to move around in the cochlea and then the hairs get bent. They are mechanoreceptors because the actual physical movement is what causes the signal to become transduced. The movement causes depolarization to happen by ions (forgot whether its Na+ or K+). The signal gets carried by the vestibularcochlear nerve.

 

[aldol16]

Different parts of the basilar membrane are most sensitive to different frequencies. The location of the vibration determines the frequency our brain perceives.

 

[coda4451]

So its just the scala tympani region that detects the frequency because its the part of the cochlea that has the basilar membrane correct?