Importance of onset properties on spectral contrast for speech and other complex spectra

Abstract

Previous studies using speech and nonspeech analogs have shown that auditory mechanisms that enhance spectral contrast serve to compensate for assimilation of spectral composition caused by coarticulated production. In the present studies, series of CV syllables varying acoustically in F2-onset frequency and perceptually from /ba/ to /da/ were identified either following [e] (higher F2) and [o] (lower F2) or following spectral complements of these vowels. Spectral complements had troughs replacing peaks corresponding to formants in the vowels. Both preceding vowels and spectral complements altered perception of the following stop, with complementary spectra providing results complementary to those for vowel spectra. However, effects for preceding spectral complements differed from those for preceding vowels by being dependent upon the precursor duration or inter-stimulus interval (ISI). Additional experiments using short spectral samples revealed that the single most important predictor of effects of vowel complements was the interval between the onset of the preceding sound and the onset of the following CV. This finding appears to implicate spectral characteristics of onsets (in addition to or instead of simple adaptation or masking) as being important for spectral contrast. The significance of these findings for the perception of connected speech will be described. [Work supported by NIDCD.]