The basilar membrane within the cochlea plays a critical role in frequency discrimination and sound perception. Different parts of this membrane resonate with different sound frequencies, shaping how the auditory system encodes sound.

Characteristics of Basilar Membrane Response to 100 Hz Sound

The basilar membrane’s mechanical properties vary along its length:

• Base of the membrane: Narrow and stiff, tuned to high frequencies.

• Apex of the membrane: Wide and flexible, tuned to low frequencies.

Traveling Wave Mechanics

When a sound wave at 100 Hz (a low frequency) enters the cochlea:

• A traveling wave propagates from the base towards the apex of the basilar membrane.

• The membrane’s resonance to low frequencies occurs near the apex, where the membrane is widest and most flexible.

• This results in maximum displacement near the apex for low-frequency sounds like 100 Hz.wikipedia+1

Analyzing the Statements

• A. The base of basilar membrane showed resonance.
  Incorrect. The base is tuned to high frequencies, not low frequencies like 100 Hz.

• B. The apex of basilar membrane showed resonance.
  Correct. The apex resonates best with low-frequency sounds.

• C. A wave travelled from base to apex, with maximum displacement near apex.
  Correct. Traveling waves progress from base to apex, peaking near the apex for low frequencies.

• D. A wave traveled from base to apex with maximum displacement near base.
  Incorrect. Maximum displacement for low-frequency sounds occurs near the apex, not the base.

Final Decision

The correct statements based on the basilar membrane’s response to 100 Hz sound are:

(2) B and C

Summary

Low-frequency sounds such as 100 Hz produce traveling waves on the basilar membrane that peak near the apex, reflecting the tonotopic organization of the cochlea. High frequencies peak near the base, while low frequencies resonate at the apex. This mechanical frequency dispersion underlies sound pitch perception in hearing.