ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

4pPP4. Fletcher and the power spectrum model of hearing.

Robert P. Carlyon

MRC Appl. Psych. Unit, 15 Chaucer Rd., Cambridge CB2 2EF, England

Fletcher's famous band-widening experiment demonstrated that the masking of a pure tone by a continuous broadband noise was determined only by those components of the noise close to the signal frequency. This formed the basis of the pervasive ``power spectrum'' model of hearing, according to which the threshold of a signal of a given frequency is determined by the amount of masker energy passing through an auditory filter centered on that frequency. This rigorous prediction has aided the identification of additional forms of auditory processing, which have been revealed by exceptions to the power spectrum model. The interpretation of such findings, which include CMR, profile analysis, informational masking, and the overshoot effect, is greatly facilitated by the existence of a ``default'' model which accounts for a large amount of other data. In addition to reviewing these developments, new evidence will be presented demonstrating that the shape of a masker's excitation pattern can also be affected by the shape of its (temporal) envelope.