Evidence for F0 preplanning with delayed stimuli

Abstract

A sentence production experiment was conducted to investigate F0 preplanning, specifically examining whether speakers plan pitch targets according to utterance length and whether preplanning limits dynamic control of pitch range. The experiment used a novel elicitation method in which visual stimuli that cue part of the utterance are delayed so that participants initiate the utterance without knowledge of its length. Participants read sentences in which the subject noun phrase was composed of one, two, or three conjoined noun phrases with controlled lexical and phonological content (e.g. Eight red weasels and nine green rhinos and eight blue llamas live in the zoo). On half of the trials with two and three noun phrases, the presentation of the visual stimuli that cued non-initial phrases (e.g., nine green rhinos and eight blue llamas) was delayed until after detection of utterance initiation. The effects of length and delay on F0 measures were analyzed. The results showed the length effect; the utterance-initial F0 peak was highest when three phrases were presented initially and lowest when one phrase was presented initially. Moreover, the utterance-initial peak in delayed stimuli was similar to that of the single phrase stimuli. In non-initial phrases, the pitch range of the delayed stimuli was constrained such that the F0 peak of the stimuli without delay was higher than those with delay. The findings suggest that speakers plan F0 targets and range before production, and such planning restricts subsequent control of F0.