Effects of frequency-shifted feedback on the pitch of vocal productions.

Previous investigations into the effects of distorted auditory feedback on vocalizations have been limited to manipulations of intensity, background noise, temporal delay, or to selective filtering of frequency. The current study reports the results of real-time shifts of the frequency components of auditory feedback. Subjectively, such shifts are perceived primarily as an alteration in the fundamental frequency (F0) of the speech. Subjects performed a variety of tasks under conditions where they received either normal auditory feedback or frequency-shifted feedback. Under normal feedback conditions, subjects maintained approximately constant F0 as instructed. With frequency-shifted feedback, subjects attempted to compensate for the shift by adjusting their F0 up or down such that the resulting feedback appeared to be "normal."