ASA 124th Meeting New Orleans 1992 October

1aSP1. Discrimination of short speech-like formant transitions.

Astrid van Wieringen

Louis C. W. Pols

Inst. of Phonetic Sci., Univ. of Amsterdam, Herengracht 338, 1016 CG, Amsterdam, The Netherlands

In a series of experiments frequency and duration discrimination thresholds of short, linear rising or falling, speech-like transitions were determined by means of same/different paired comparison tasks. Difference limens of single formant transitions varying in frequency extent at a constant duration (experiment 1), decreased with increase of transition duration. They were, on average, 70, 63, and 57 Hz for 20, 30, and 50 ms, respectively. However, when transition duration varied at a constant frequency extent (experiment 2), difference limens were, on average, 2.7, 4.5, and 4.9 ms for standard transitions of 20, 30, and 50 ms, respectively. In both experiments, thresholds between rising and falling transitions, determined in two frequency regions, and between transitions with either higher or lower rates of frequency change than the standard transition, were comparable. The extent to which the first formant transition and the steady-state interfere with discrimination of the second formant transition is studied further with single and combined formants, bounded by plateaus (experiment 3). The data suggest that, although transition rate is varied, different psychoacoustical cues are extracted by the auditory mechanism.