The effect of altered sentence rhythm on timing judgments

Abstract

Successful speech understanding requires the listener to accurately anticipate the temporal onsets of individual words in running speech. The present study investigated listeners’ sensitivity to temporal deviations in sentences with natural or modified speech timing. Subjects listened to sentences in which a portion of speech preceding the final word was replaced by a silent gap. On each trial, an intact sentence was presented, followed by two versions of the sentence with a silent gap: one with the correct timing for the gap (i.e., equal to the duration of the missing speech) and one with altered gap timing (longer or shorter than the missing speech). Listeners judged which version had the altered timing. An adaptive procedure was used to estimate thresholds for the detection of altered timing for early-onset (shortened gap) and late-onset (lengthened gap) final words. In separate conditions, the rhythm of the sentence preceding the gap was either unaltered or rate-modulated according to a sinusoidal modulator. Results showed that the ability to identify the correct gap timing was adversely affected by the manipulation of sentence rhythm, and in both intact and altered rhythmic contexts, listeners were better at detecting early final word onsets than late onsets.