Vocal analysis related to changes in frequency of pure tone auditory feedback.

Purpose: Many studies have shown that subjects show a change of vocal fundamental frequency (F0) when phonating subjects hear their vocal pitch feedback shifted upward or downward. This study was performed to demonstrate whether vocal parameters [F0, intensity, jitter, shimmer, and noise to harmonic ratio (NHR)] in normal males respond to changes in frequency of pure tone masking.

Materials And Methods: Twenty healthy male subjects participated in this study. Subjects vocalized /a/ vowel sounds while listening to a pitch- shift pure tone through headphones (upward pitch-shift in succession: 1 kHz to 2 kHz and 1 kHz to 4 kHz at 50 dB or 80 dB, respectively, downward pitch-shift in succession: 1 kHz to 250 Hz and 1 kH to 500 Hz at 50 dB or 80 dB, respectively).

Results: Vocal intensity, F0, was increased, whereas jitter was decreased as the pitch of pure tone was shifted upward. However, there was no correlation between shimmer and NHR with pitch-shift feedback for pure tones. Unlike vocal pitch- shift feedback in other studies, upward pitch-shift feedback of pure tones caused the vocal F0 and intensity to change in the same direction as pitch-shift.

Conclusion: The results of this study demonstrated that auditory kinesthetic feedback is affected by pitch-shift in pure tone.