The range of inner hair cells (IHCs) recruited for soft sounds is?

The range of inner hair cells (IHCs) recruited for soft sounds is?

• A. All IHCs
• B. 4-6 IHCs
• C. 7-9 IHCs
• D. 1-3 IHCs

Answer: (D)

Soft sounds are detected by a very small subset of inner hair cells. The basilar membrane motion at low intensities is localized around the characteristic place for a given frequency, so only a few neighboring IHCs reach their transduction threshold and fire. Outer hair cells boost sensitivity, but they don’t substantially broaden which IHCs are activated at these low levels. As the sound grows louder, more IHCs in adjacent areas cross threshold, expanding the pool of active cells, but at soft levels the activation remains limited to a small cluster. Therefore, the range of inner hair cells recruited for soft sounds is 1-3 IHCs.

Soft sounds are detected by a very small subset of inner hair cells. The basilar membrane motion at low intensities is localized around the characteristic place for a given frequency, so only a few neighboring IHCs reach their transduction threshold and fire. Outer hair cells boost sensitivity, but they don’t substantially broaden which IHCs are activated at these low levels. As the sound grows louder, more IHCs in adjacent areas cross threshold, expanding the pool of active cells, but at soft levels the activation remains limited to a small cluster. Therefore, the range of inner hair cells recruited for soft sounds is 1-3 IHCs.