How many inner hair cells are recruited for moderate-intensity sounds?

How many inner hair cells are recruited for moderate-intensity sounds?

• A. 8-12+ IHCs
• B. 4-7 IHCs
• C. 2-3 IHCs
• D. 10-15 IHCs

Answer: (B)

Moderate-intensity sounds activate only a small cluster of inner hair cells around the region of the cochlea tuned to the sound’s frequency. Each inner hair cell transduces mechanical motion into neural signals, and while many fibers follow each cell, the basilar membrane’s displacement at moderate levels is limited, so only a handful of neighboring inner hair cells reach the threshold to contribute to the response. This typically corresponds to about four to seven inner hair cells being recruited. If the intensity increases further, more adjacent inner hair cells begin to respond, but at moderate levels the system relies on a modest, localized group to encode the signal. Numbers much lower (2–3) would underrepresent the neural drive for a moderate sound, while numbers much higher (8–12 or 10–15) would reflect broader spread seen at higher intensities rather than moderate ones.

Moderate-intensity sounds activate only a small cluster of inner hair cells around the region of the cochlea tuned to the sound’s frequency. Each inner hair cell transduces mechanical motion into neural signals, and while many fibers follow each cell, the basilar membrane’s displacement at moderate levels is limited, so only a handful of neighboring inner hair cells reach the threshold to contribute to the response. This typically corresponds to about four to seven inner hair cells being recruited. If the intensity increases further, more adjacent inner hair cells begin to respond, but at moderate levels the system relies on a modest, localized group to encode the signal. Numbers much lower (2–3) would underrepresent the neural drive for a moderate sound, while numbers much higher (8–12 or 10–15) would reflect broader spread seen at higher intensities rather than moderate ones.