Asynchrony tolerance in the perceptual organization of speech.

Researchers have claimed that listeners tolerate large temporal distortion when integrating the spectral components of speech. In some estimates, perceivers resolve linguistic attributes at spectral desynchronies as great as the duration of a syllable. We obtained new measures of perceptual tolerance of auditory asynchrony, using sine-wave synthesis in order to require perceivers to resolve the speech stream dynamically. Listeners transcribed sentences in which the tone analogue of a second formant was desynchronized relative to the remaining tones of a sentence, with desynchrony ranging from a 250-msec lead to a 250-msec lag. Intelligibility declined symmetrically from 72% at synchrony to 7% at +/-100 msec. This finding of narrow asynchrony tolerance indicates a time-critical feature of the auditory perceptual organization of speech.