Outer hair cells actively amplify and sharpen frequency response without signaling the brain.

Evidence

The outer hair cells are active—that is, they can both respond to the shearing of the two membranes that they link and in turn affect the shearing by contracting, by a feedback mechanism. It is thought that this feedback plays two roles: (1) a kind of preamplifier for soft sounds, amplifying them for the inner hair cells, which create the signals sent to the brain, and (2) to sharpen frequency response, even when the sound is quite loud and needs no preamplification. Outer hair cells do not send neural signals to the brain. — Eric J. Heller, Why You Hear What You Hear- An…, 1960

Categorization

Category: Causal Relationships

• XREF: This is the active feedback that resolves the Q/time tradeoff noted at 1957-1959 — mechanical imprecision corrected neurally.

Related

• Outer hair cells actively amplify and sharpen sound before inner hair cells fire (similarity 0.91)
• Outer hair cells sit where basilar membrane vibration is greatest (similarity 0.87)
• Auditory feedback amplification occurs at hair cells, not in the brain (similarity 0.87)
• Outer haircells amplify quiet sounds only, while inner haircells respond directly to loud ones. (similarity 0.86)
• Outer hair cells provide active frequency-selective amplification in the cochlea (similarity 0.85)
• Feedback in outer haircells enhances sensitivity while lateral spread shapes frequency selectivity. (similarity 0.84)
• Hair cells actively amplify cochlear vibration rather than only sensing it (similarity 0.83)
• Cochlear outer hair cells enable speech amid noise and reverberation (similarity 0.83)
• Neural feedback restores sharp frequency resolution that hair cells lack on their own (similarity 0.82)
• Outer haircells act locally within the cochlea to modulate inner haircells (similarity 0.82)
• Outer hair cell damage explains recruitment by disabling active cochlear gain (similarity 0.82)
• Outer hair cells act as nonlinear amplifiers with bidirectional lateral feedback (similarity 0.82)
• Outer hair cells encode displacement and therefore stay responsive at low frequencies. (similarity 0.82)
• Inner hair cells only convert oscillations to spike rates in the model (similarity 0.81)
• Outer hair cells respond better than inner hair cells to low-frequency sound (similarity 0.81)