Psychophysical Investigation of the Auditory Periphery

University Of California-Irvine, Irvine CA

Investigators

Abstract

For the past 60 years, the peripheral auditory system has been modeled as a bank of bandpass filters, which is analogous to a graphic equalizer on a high-end stereo system. Some filters respond only to low frequencies whereas other filters respond only to high frequencies. In effect, the output from the filterbank represents a rough analysis of the spectral content of the input, which is critical information for discriminating and identifying sounds. However, a number of key experiments during the last few years have shown that a single filterbank model is too simplistic. Acoustic information exists in different forms that require different processing mechanisms. A more sophisticated view of the auditory system, that holds much promise, is one of multiple parallel processes. The envelope of the sound waveform, for instance, contains much useful information and requires a temporal analysis rather than a spectral analysis. This research introduces the theory that temporal and spectral processes have distinct filtering mechanisms that operate in parallel. There is some psychophysical data to support this idea but a more thorough investigation is needed to lay the groundwork for developing a theory that is sufficiently complete to have practical applications. For example, a complete understanding of the filtering properties of the auditory system is crucial for improving the design of cochlear implants and hearing aids.