### ASA 127th Meeting M.I.T. 1994 June 6-10

## 2aPP4. Global and local parameter and response attributes in a box-cochlea
model.

**Timothy A. Wilson
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*Room No. 204A, Eng. Sci. Bldg., Dept. of Elec. Eng., Memphis State Univ.,
Memphis, TN 38152
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**William M. Siebert
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*MIT, Cambridge, MA 02139
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The similarities and distinctions among linear, passive, cochlear models
of one-, two-, and three-dimensional fluid motion---models popularized by
(among others) Zwislocki, Ranke, and Steele, respectively---are confounded by
fuzzy terminology (e.g., ``long-wave'' and ``short-wave''). Such models are
frequently evaluated by comparing their place responses with measured frequency
responses; their global impedance parameters are sometimes chosen solely to
secure fit to local observations. Steele's WKB (phase-integral) approach is
often treated as a technique for solving cochlear dynamical equations rather
than as a conceptual framework yielding insight into cochlear phenomena. In
this presentation, cochlear dynamical equations are developed for one-, two,
and three-dimensional fluid motion in a box-cochlea model. The phase-integral
approximate solution to these equations is described; the utility of this
framework for explaining cochlear phenomena is discussed. Generalized
representations for both cochlear-partition impedance and cochlear-gain
response are developed highlighting the similarities and distinctions between
the place response at a single frequency and the frequency response at a single
place. The generalized representations clarify which aspects of partition
impedance determine global features such as cochlear maps and which aspects
determine local features such as magnitude-response peakiness and
phase-response steepness.