Britannica Sources used in this answer

Why can damage to outer hair cells make quiet sounds harder to hear?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Diagram showing auditory mechanisms in insects, including labeled illustrations of a scolophore organ, the mosquito ear with antenna shaft and scolophores, the cicada ear with auditory capsule and tympanic membrane, and the grasshopper ear with sensory body and tympanic membrane. — sound reception Auditory mechanisms in insects. (Left) A scolophore organ. (Top right) The mosquito ear. (Centre right) The ear of the cicada *Magicicada septendecim*. (Bottom right) The ear of the grasshopper.

Outer hair cells play a critical role in hearing by acting as mechanical-electrical stimulators and feedback elements that modify and enhance the sensitivity of inner hair cells.1

Because inner hair cells are positioned on the bony shelf of the osseous spiral lamina rather than the basilar membrane, they are less easily stimulated by sound vibrations on their own. Outer hair cells help bridge this gap by contracting rhythmically in response to sound, which effectively amplifies the stimulus for the inner hair cells. When outer hair cells are damaged or destroyed, this amplification mechanism is lost, causing the threshold required to trigger the inner hair cells to rise significantly—often by as much as 40 dB—thereby making quiet sounds much harder to detect.1