Evoked otoacoustic emissions as cochlear Bragg reflections

The reflection of cochlear waves is mathematically described for various assumptions about the dependence of the echo-generating mechanism on place and frequency, without requiring knowledge of the physical details of the mechanism. Any 'wave-related' reflections, caused by intrinsic features of the resonance or active-feedback mechanism, cannot explain long group delays in an approximately shift-similar basilar membrane (BM). Only 'BM related' scattering due to inhomogenities is a possible explanation then. Reflection at a fixed point of the BM could cause only narrow-band evoked otoacoustic emissions (EOAEs). Long group delays in a wider frequency band can be obtained by assuming Bragg reflection at an approximately periodic inhomogenity of BM parameters, possibly due to spatial variations of active undamping. This explains the long delays, about inversely proportional to frequency, the decreasing instantaneous frequency, the often found multi-packet or modulated structure of echoes (vanishing at higher SPL), the spectra of simultaneous and delayed EOAEs and their relation to the threshold of hearing. These phenomena do not necessarily require multiple reflection due to middle/inner-ear mismatch.

[1]  E. Zwicker.  Delayed evoked oto-acoustic emissions and their suppression by Gaussian-shaped pressure impulses , 1983, Hearing Research.

[2]  Analysis and Influence of Lidocaine on Evoked Otoacoustic Emissions from Tinnitus Sufferers , 1989 .

[3]  R. Freyman,et al.  Spontaneous and impulsively evoked otoacoustic emission: indicators of cochlear pathology? , 1983, Hearing Research.

[4]  M R Schroeder,et al.  An integrable model for the basilar membrane. , 1973, The Journal of the Acoustical Society of America.

[5]  R. Guelke,et al.  A mechanism for stimulated acoustic emissions in the cochlea , 1985, Hearing Research.

[6]  E. de Boer,et al.  Wave propagation and dispersion in the cochlea , 1984, Hearing Research.

[7]  D. T. Kemp,et al.  Properties of the generator of stimulated acoustic emissions , 1980, Hearing Research.

[8]  Eberhard Zwicker,et al.  Evaluating Traveling Wave Characteristics in Man by an Active Nonlinear Cochlea Preprocessing Model , 1986 .

[9]  D. Kemp.  Stimulated acoustic emissions from within the human auditory system. , 1978, The Journal of the Acoustical Society of America.

[10]  R. J. Ritsma,et al.  Evoked acoustical responses from the human ear: Some experimental results , 1980, Hearing Research.

[11]  E Zwicker,et al.  "Otoacoustic" emissions in a nonlinear cochlear hardware model with feedback. , 1986, The Journal of the Acoustical Society of America.

[12]  E. Zwicker,et al.  Acoustical responses and suppression-period patterns in guinea pigs , 1981, Hearing Research.

[13]  R. J. Ritsma,et al.  FREQUENCY-SPECTRA OF COCHLEAR ACOUSTIC EMISSIONS (KEMP-ECHOES) , 1981 .

[14]  E. de Boer,et al.  Validity of the Liouville-Green (or WKB) method for cochlear mechanics , 1982, Hearing Research.

[15]  A. Papoulis.  Systems and transforms with applications in optics , 1981 .

[16]  J. Zwislocki.  Sharp vibration maximum in the cochlea without wave reflection , 1983, Hearing Research.

[17]  E. Zwicker.  Das Innenohr als aktives schallverarbeitendes und schallaussendendes System , 1985 .

[18]  E Zwicker,et al.  Interrelation of different oto-acoustic emissions. , 1984, The Journal of the Acoustical Society of America.

[19]  Kemp Dt,et al.  The evoked cochlear mechanical response and the auditory microstructure - evidence for a new element in cochlear mechanics. , 1979 .

[20]  E. Zwicker.  Otoacoustic Emissions and Cochlear Travelling Waves , 1989 .

[21]  J. W. Horst,et al.  Psychophysical Aspects of Cochlear Acoustic Emissions (“Kemp-Tones”) , 1938 .

[22]  J. P. Wilson,et al.  Evidence for a cochlear origin for acoustic re-emissions, threshold fine-structure and tonal tinnitus , 1980, Hearing Research.

[23]  J. Pickles.  An Introduction to the Physiology of Hearing , 1982 .

[24]  S. D. Anderson.  Some ECMR properties in relation to other signals from the auditory periphery , 1980, Hearing Research.

[25]  W. L. C. Rutten,et al.  Evoked acoustic emissions from within normal and abnormal human ears: Comparison with audiometric and electrocochleographic findings , 1980, Hearing Research.

[26]  W. Peisl.  Simulation von zeitverzögerten evozierten oto-akustischen Emissionen mit Hilfe eines digitalen Innenohrmodells , 1988 .

[27]  R. J. Ritsma,et al.  Stimulated acoustic emissions from the human ear , 1979 .

[28]  J. P. Wilson,et al.  Model for cochlear echoes and tinnitus based on an observed electrical correlate , 1980, Hearing Research.