Effects of pitch-shift velocity on voice F0 responses

Previous studies have shown that voice fundamental frequency (F-0) is modified by changes in the pitch of vocal feedback and have demonstrated that the;audio-vocal control system has both open- and closed-loop control properties. However, the extent to which this system operates in closed-loop fashion may have been underestimated in previous work. Because the step-type stimuli used were very rapid, and people are physically unable to change their voice F-0 as rapidly as the stimuli, feedback responses might have been reduced or suppressed. In the present study, pitch-shift stimuli, consisting of a disparity between voice F-0 and feedback pitch of varying ramp onset velocities, were presented to subjects vocalizing a steady \ah\ sound to examine the effect of stimulus onset on voice F-0 responses. Results showed that response velocity covaried with stimulus velocity. Response latency and time of the peak response decreased with increases in stimulus velocity, while response magnitude decreased. A simple- feedback model reproduced most features of these responses. These results strongly support previous suggestions that the audio-vocal system monitors auditory feedback and, through closed-loop negative feedback, adjusts voice F-0 so as to cancel low-level fluctuations in F-0. (C) 2000 Acoustical Society of America. (C) 2000 Acoustical Society of America. [S0001-4966(00)05601-0].