Loud sound-induced changes in cochlear mechanics

Anders Fridberger, Jiefu Zheng, Anand Parthasarathi, Tianying Ren, Alfred Nuttall

Research output: Contribution to journalArticle

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Abstract

To investigate the inner ear response to intense sound and the mechanisms behind temporary threshold shifts, anesthetized guinea pigs were exposed to tones at 100-112 dB SPL. Basilar membrane vibration was measured using laser velocimetry, and the cochlear microphonic potential, compound action potential of the auditory nerve, and local electric AC potentials in the organ of Corti were used as additional indicators of cochlear function. After exposure to a 12-kHz intense tone, basilar membrane vibrations in response to probe tones at the characteristic frequency of the recording location (17 kHz) were transiently reduced. This reduction recovered over the course of 50 ms in most cases. Organ of Corti AC potentials were also reduced and recovered with a time course similar to the basilar membrane. When using a probe tone at either 1 or 4 kHz, organ of Corti AC potentials were unaffected by loud sound, indicating that transducer channels remained intact. In most experiments, both the basilar membrane and the cochlear microphonic response to the 12-kHz overstimulation was constant throughout the duration of the intense stimulus, despite a large loss of cochlear sensitivity. It is concluded that the reduction of basilar membrane velocity that followed loud sound was caused by changes in cochlear amplification and that the cochlear response to intense stimulation is determined by the passive mechanical properties of the inner ear structures.

Original languageEnglish (US)
Pages (from-to)2341-2348
Number of pages8
JournalJournal of neurophysiology
Volume88
Issue number5
DOIs
StatePublished - Nov 1 2002

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ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology

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