Where are high-frequency sounds encoded along the basilar membrane?

Where are high-frequency sounds encoded along the basilar membrane?

• A. Apex
• B. Middle region
• C. Base of the basilar membrane
• D. Throughout uniformly

Answer: (C)

High-frequency sounds are encoded at the base of the basilar membrane because the base is stiffer and narrower, making it the place where high-frequency vibrations produce the maximum displacement. The cochlea uses a tonotopic map: as frequency increases, the peak of the traveling wave occurs closer to the base, so hair cells there are selectively stimulated by high tones. In contrast, the apex and mid-region are tuned to lower frequencies, and a uniform encoding would ignore this organized spatial pattern. So the base of the basilar membrane is where high-frequency information is most strongly represented.

High-frequency sounds are encoded at the base of the basilar membrane because the base is stiffer and narrower, making it the place where high-frequency vibrations produce the maximum displacement. The cochlea uses a tonotopic map: as frequency increases, the peak of the traveling wave occurs closer to the base, so hair cells there are selectively stimulated by high tones. In contrast, the apex and mid-region are tuned to lower frequencies, and a uniform encoding would ignore this organized spatial pattern. So the base of the basilar membrane is where high-frequency information is most strongly represented.