Cochlear Macromechanical Modelling
Abstract
Contemporary research into the manifestations and origins of nonlinear, active cochlear processes often takes place in a context in which linear, passive cochlear mechanics are poorly understood and poorly communicated. The distinctions among models of one, two, and threedimensional fluid motion in the cochlear scalamodels popularized by (among others) Zwislocki, Ranke, and Steele, respectively are confounded by fuzzy use of terms such as "longwave model" or "shortwave model." Models are frequently evaluated by comparing their place responses with experimentally observed frequency responses; their global impedance parameters are sometimes chosen solely to secure fit to some local measurement. And Steele's WKB (phaseintegral) approach is treated, more often than not, as just another technique for solving cochlear dynamical equations, rather than as a conceptual framework yielding significant insight into cochlear phenomena. In this thesis, I present cochlear dynamical equations for one, two, and threedimensional fluid motion in a boxcochlea model, and I discuss the conditions under which such fluid motion is appropriately described as long wave, short wave, or as something in between. I describe the phaseintegral approximate solution to these equations and discuss the utility of this framework for explaining cochlear phenomena. I develop generalized representations for both cochlearpartition impedance and cochleargain response that highlight the distinctions and similarities 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 phenomena, such as cochlear maps, and which aspects determine local features, such as magnitude response peakiness and phaseresponse steepness. (Copies available exclusively from MIT Libraries, Rm. 140551, Cambridge, MA 021394307. Ph. 6172535668; Fax 617253 1690.).
 Publication:

Ph.D. Thesis
 Pub Date:
 1994
 Bibcode:
 1994PhDT........70W
 Keywords:

 FLUID MOTION;
 Biophysics: General; Physics: Acoustics; Engineering: Electronics and Electrical