Basilar-membrane responses to tones at the base of the chinchilla cochlea

J Acoust Soc Am. 1997 Apr;101(4):2151-63. doi: 10.1121/1.418265.


Basilar-membrane responses to single tones were measured, using laser velocimetry, at a site of the chinchilla cochlea located 3.5 mm from its basal end. Responses to low-level (< 10-20 dB SPL) characteristic-frequency (CF) tones (9-10 kHz) grow linearly with stimulus intensity and exhibit gains of 66-76 dB relative to stapes motion. At higher levels, CF responses grow monotonically at compressive rates, with input-output slopes as low as 0.2 dB/dB in the intensity range 40-80 dB. Compressive growth, which is significantly correlated with response sensitivity, is evident even at stimulus levels higher than 100 dB. Responses become rapidly linear as stimulus frequency departs from CF. As a result, at stimulus levels > 80 dB the largest responses are elicited by tones with frequency about 0.4-0.5 octave below CF. For stimulus frequencies well above CF, responses stop decreasing with increasing frequency: A plateau is reached. The compressive growth of responses to tones with frequency near CF is accompanied by intensity-dependent phase shifts. Death abolishes all nonlinearities, reduces sensitivity at CF by as much as 60-81 dB, and causes a relative phase lead at CF.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acoustic Stimulation
  • Animals
  • Basilar Membrane / physiology*
  • Cell Death
  • Chinchilla / physiology*
  • Cochlea / physiology*