The role of peak amplitude in vowel recognition

Abstract

Many theories of speech perception rely on the loci of spectral peaks as at least one factor upon which pattern recognition is based. However, when a peak is lower in amplitude than its neighbors, it may not be used in phonetic recognition. In the first experiment, a [u]-[i] series was constructed by manipulating the amplitude of a spectral peak (851 Hz). Subjects readily identified an item from the series with a low-amplitude, 851-Hz spectral peak as an [i]. It would appear that this peak, at a low amplitude, is not used at a phonetic level of processing. Further experiments test the perceptual locus of the use (or nonuse) of this low-amplitude peak information. Selective adaptation experiments were run in which the adaptors, including the [i] from the first experiment, varied in spectral overlap with a [u]-[u] test series in order to determine the degree to which the low-amplitude, 851-Hz peak is utilized in processing. The results will be discussed in terms of how peaks are analyzed at different levels of processing and how this relates to various theories of speech perception. [Work supported by NIDCD DC00219.]