Auditory physics. Physical principles in hearing theory. II

Abstract

In the first part of this series of papers [Phys. Reports 62 (1980) 87–174] several physical problems are described that are relevant for the study of the auditory system. The present paper extends this treatment, it describes more facts upon which auditory theory is to be based and it delves considerably deeper into the mechanics of the cochlea (inner ear). The first two chapters treat nonlinear phenomena that are found in physiological and mechanical responses of the cochlea and in psychophysical experiments (listening tests carried out in human subjects). The main part of the paper is devoted to the mechanics of the cochlea. This part is preceded by an overview of the results of mechanical measurements on the cochlea. As it turns out, the newest experimental data present a specific challenge for cochlear mechanics. The central three chapters of the paper describe the development of a linear three-dimensional model of the cochlea. The main intention is to describe this model in a step-by-step fashion (hence the chapter headings borrowed from the field of architecture). Even in this simplified case, the solution for the response of the cochlear model is far from easy. Therefore, a few excursions are made into fields of physics and engineering in which related problems are worked out in analytical form. Just as in Part I of this series of papers, this extended treatment considerably deepens insight into the physical factors involved. Confrontation of the requirements for modelling described in the first few chapters with what has been achieved in the final part reveals how much study in the field of auditory physics remains to be done.