Cochlear Physiology

What is Condensation/Compression

Molecules are forced to pressed together

What is rarefaction

Molecules have extra space and allowed to expand

This causes transverse displacement along the BM

Condensation waves drive the BM downward

Rarefaction waves drive the BM upward

Frequency of a stimulus is represented by what

Location of maximum displacement of the BM

Basal end of BM

thicker and more narrow (stiffer)

fast movements

better in high frequencies

Apical end of BM

thinner and wider (less stiff)

slow movements

better in low frequencies

Where does maximum displacement of a traveling wave occur

The resonant frequency on the BM

TW dies quickly beyond the resonance point

Do low frequency sounds or high freq sounds travel farther

Low freq. because they need to travel to the apex of the BM

Upward spread of masking

When low frequency sounds mask the high frequency sounds

Can happen if lows are boosted too much and the speech frequencies are masked

Increase in intensity means what with the BM

represented by the amount of BM deflection

Peak displacement grows and becomes broader

Linear vs nonlinear gain, and what is the BM?

1:1 vs not 1:1.

BM is nonlinear

Why is the nonlinear compression function important

Serves as a protective mechanism for the organ of Corti

Healthy cochlea is highly frequency what?

Highly frequency selective

Soft or loud sounds more frequency specific?

soft sounds

Tonotopic organization of cochlea

separates frequencies from base to apex

low pitches in the apical region

high pitches in the basal region