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Titolo:
Intensity-invariance of fine time structure in basilar-membrane click responses: Implications for cochlear mechanics
Autore:
Shera, CA;
Indirizzi:
Massachusetts Eye & Ear Infirm, Eaton Peabody Lab Auditory Physiol, Boston, MA 02114 USA Massachusetts Eye & Ear Infirm Boston MA USA 02114 , Boston, MA 02114 USA Harvard Univ, Sch Med, Dept Otol & Laryngol, Boston, MA 02115 USA Harvard Univ Boston MA USA 02115 pt Otol & Laryngol, Boston, MA 02115 USA
Titolo Testata:
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
fascicolo: 1, volume: 110, anno: 2001,
pagine: 332 - 348
SICI:
0001-4966(200107)110:1<332:IOFTSI>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
AUDITORY-NERVE FIBERS; OUTER HAIR-CELLS; 3-DIMENSIONAL MODEL; FREQUENCY-SELECTIVITY; MOSSBAUER TECHNIQUE; CHINCHILLA COCHLEA; IMPULSE RESPONSES; WAVE-FORM; STIMULI; GLIDES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Engineering, Computing & Technology
Citazioni:
50
Recensione:
Indirizzi per estratti:
Indirizzo: Shera, CA Massachusetts Eye & Ear Infirm, Eaton Peabody Lab Auditory Physiol, 243 Charles St, Boston, MA 02114 USA Massachusetts Eye & Ear Infirm 243Charles St Boston MA USA 02114
Citazione:
C.A. Shera, "Intensity-invariance of fine time structure in basilar-membrane click responses: Implications for cochlear mechanics", J ACOUST SO, 110(1), 2001, pp. 332-348

Abstract

Basilar-membrane and auditory-nerve responses to impulsive acoustic stimuli, whether measured directly in response to clicks or obtained indirectly using cross- or reverse-correlation and/or Fourier analysis, manifest a striking symmetry: near-invariance with stimulus intensity of the fine time structure of the response over almost the entire dynamic range of hearing. This paper explores the origin and implications of this symmetry for cochlear mechanics. Intensity-invariance is investigated by applying the EQ-NL theorem [de Beer, Aud. Neurosci. 3, 377-388 (1997)] to define a family of linearcochlear models in which the strength of the active force generators is controlled by a real-valued, intensity-dependent parameter, gamma (with 0 less than or equal to gamma less than or equal to1). The invariance of fine time structure is conjectured to imply that as gamma is varied the poles of the admittance of the cochlear partition remain within relatively narrow bands of the complex plane oriented perpendicular to the real frequency axis. Physically, the conjecture implies that the local resonant frequencies of the cochlear partition are nearly independent of intensity. Cochlear-model responses, computed by extending the model obtained by solution of the inverse problem in squirrel monkey at low sound levels [Zweig, J. Acoust. Sec. Am. 89, 1229-1254 (1991)] with three different forms of the intensity dependence of the partition admittance, support the conjecture. Intensity-invariance of cochlear resonant frequencies is shown to be consistent with the well-known "half-octave shift," describing the shift with intensity in the peak (or best) frequency of the basilar-membrane frequency response. Shifts inbest frequency do not arise locally, via changes in the underlying resonant frequencies of the partition, but globally through the intensity dependence of the driving pressure. Near-invariance of fine time structure places strong constraints on the mechanical effects of force generation by outer hair cells. In particular, the symmetry requires that the feedback forces generated by outer hair cells (OHCs) not significantly affect the natural resonant frequencies of the cochlear partition. These results contradict many, if not most, cochlear models, in which OHC forces produce significant changes in the reactance and resonant frequencies of the partition. (C) 2001 Acoustical Society of America.

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Documento generato il 26/11/20 alle ore 10:48:11