Cochlear Waves: Interaction Between Theory and Experiments

Review of past experimental and theoretical research leads to a statement of our present knowledge of cochlear mechanics. In particular, an attempt is made at a clear definition of the nature of cochlear waves. With the help of prominent examples, it is shown that neither experiments nor theory have ever been entirely correct but have supplemented and corrected each other mutually in steps of successive approximation. As the approximation has become closer, the steps have become smaller, but the process is still going on. During the Békésy era, the weight of research was on the fundamental properties of cochlear waves; now, the emphasis is on numerical values of such parameters as wavelength, damping, and nonlinearity. At the end of the presentation, some effects of the cochlear wave pattern on auditory neural excitation are discussed. Especially, it is shown how displacement and velocity responses can be separated by means of appropriate stimulus patterns.