Auditory versus phonetic accounts of observed confusions between consonant phonemes.

The utility of phonetic features versus acoustic properties for describing perceptual relations among speech sounds was evaluated with a multidimensional scaling analysis of Miller and Nicely's [J. Acoust. Soc. Am. 27, 338-352 (1955)] consonant confusions data. The INDSCAL method and program were employed with the original data log transformed to enhance consistency with the linear INDSCAL model. A four-dimensional solution accounted for 69% of the variance and was best characterized in terms of acoustic properties of the speech signal, viz., temporal relationship of periodicity and burst onset, shape of voiced first formanant transition, shape of voiced second formanant transition, and amount of initial spectral dispersion, rather than in terms of phonetic features. The amplitude and spectral location of acoustic energy specifying each perceptual dimension were found to determine a dimension's perceptual effect as the signal was degraded by masking noise and bandpass filtering. Consequently, the perceptual bases of identification confusions between pairs of syllables were characterized in terms of the shared acoustic properties which remained salient in the degraded speech. Implications of these findings for feature-based accounts of perceptual relationships between phonemes are considered.