Re-examining the effects of perturbation magnitude, direction, and duration on the pitch-shift reflex.

Abstract

Comparing average voice fundamental frequency (F0) responses to pitch-shifted auditory feedback has revealed effects of some stimulus parameters, but not of others. We hypothesize that some stimulus effects on pitch-shift reflex characteristics are spurious, the result of differences in the incidence of the pitch-shift reflex rather than its inherent characteristics. Using a template correlation analysis technique that allows the pitch-shift reflex to be identified in individual trials, the effects of stimulus magnitude, direction, and duration were re-examined. We presented 30 healthy adults with auditory feedback pitch shifts during sustained phonation of the vowel /u/. Pitch shifts were all combinations of magnitude (50, 300, and 600 cents), Direction (up and down) and duration (100 and 500 ms) for a total of 12 conditions. Results indicate significant effects of pitch perturbation magnitude and direction on the incidence of the pitch-shift reflex. Implications for our understanding of voice F0 responses to changes in auditory feedback are discussed.