Reverse wave propagation in the cochlea

Wenxuan He, Anders Fridberger, Edward Porsov, Karl Grosh, Tianying Ren

Research output: Contribution to journalArticle

52 Scopus citations

Abstract

Otoacoustic emissions, sounds generated by the inner ear, are widely used for diagnosing hearing disorders and studying cochlear mechanics. However, it remains unclear how emissions travel from their generation sites to the cochlear base. The prevailing view is that emissions reach the cochlear base via a backward-traveling wave, a slow-propagating transverse wave, along the cochlear partition. A different view is that emissions propagate to the cochlear base via the cochlear fluids as a compressional wave, a fast longitudinal wave. These theories were experimentally tested in this study by measuring basilar membrane (BM) vibrations at the cubic distortion product (DP) frequency from two longitudinal locations with a laser interferometer. Generation sites of DPs were varied by changing frequencies of primary tones while keeping the frequency ratio constant. Here, we show that BM vibration amplitude and phase at the DP frequency are very similar to responses evoked by external tones. Importantly, the BM vibration phase at a basal location leads that at a more apical location, indicating a traveling wave that propagates in the forward direction. These data are in conflict with the backward-traveling-wave theory but are consistent with the idea that the emission comes out of the cochlea predominantly through compressional waves in the cochlear fluids.

Original languageEnglish (US)
Pages (from-to)2729-2733
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume105
Issue number7
DOIs
StatePublished - Feb 19 2008

Keywords

  • Basilar membrane vibration
  • Cochlear traveling wave
  • Laser interferometer
  • Otoacoustic emission

ASJC Scopus subject areas

  • General

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