5aPP3. Otoacoustic emissions as tools to probe cochlear function.

Session: Friday Morning, May 17

Time: 9:05

Author: Glenis R. Long
Location: Dept. of Audiol. and Speech Sci., Purdue Univ., West Lafayette, IN 47907
Author: Carrick L. Talmadge
Author: Arnold Tubis
Location: Purdue Univ., West Lafayette, IN 47907


Otoacoustic emissions (acoustic signals originating in the cochlea) can be noninvasively evaluated by placing a sensitive microphone in the ear canal and extracting the emissions from the noise by signal analysis. Since first reported (Kemp, 1978), otoacoustic emissions have been developed into a very useful experimental tool for probing cochlear function. A research overview will give special attention to the existence of a strong periodicity in the frequency domain in all human otoacoustic emissions. This periodicity will be related to maxima and minima seen in hearing threshold measurements. Discussion will focus on the hypothesis that the basis for the pseudoperiodic nature of the emissions is the coherent scattering from cochlear irregularities within the tall and broad peak of the traveling wave [cf. Shera and Zweig, J. Acoust. Soc. Am. 98, 2018--2047 (1995)]. This scattering gives rise to a reflection of the cochlear wave towards the base, whose effects are detectable in the ear canal signal. The pseudoperiodic properties of emissions are governed by the nearly linear frequency dependence of the phase of the cochlear traveling wave ratio, which is mainly determined by the complex wavelength of the traveling wave in the peak region. [Work supported by NIDCD.]

from ASA 131st Meeting, Indianapolis, May 1996