CENTRAL AUDITORY-SYSTEM

A biological view of the central auditory system seems to be replacing the older Galilean or physics-based view as the guide for research in the late 20th century. This emerging view is primarily Darwinian in o rigin and recognizes that the entire auditory system is an adaptation for extracting information from natural sounds and their sources, usua lly for the guidance of immediate behavioral action. The fact that nat ural sounds themselves are almost always transients, too brief in dura tion to have tonal quality, suggests that the ear is far more of a Fas t Fourier Transformer (and less of a Fourier analyzer) than is usually explicitly stated. Since the brief sounds constituting most of the ac oustical environment contain critical information for guiding behavior al activity, several further hypotheses regarding the cell-level and t issue-level contributions of the central auditory system also follow. For example, the new view suggests that the central auditory system's role is likely to include the extraction of the behaviorally most impo rtant features, aspects, or dimensions of the sources of sounds in add ition to, or possibly instead of, the physical dimensions of the sound s themselves. Because this new view has already enjoyed some measure o f success and has also suggested a number of new and unusual direction s for future research, it may become the dominant theory for research in the 21st century.