Hideki KAWAHARA
Transformed Auditory Feedback:
Effects of Fundamental Frequency Perturbation
Abstract:A rapid interaction between auditory perception and speech production has been found using fundamental frequency perturbation to transform auditory feedback. The technique of transformed auditory feedback has been developed to keep the disturbance of normal speech production processes to a minimum, while allowing interactions between speech production and auditory perception to be detected. In the first experiment, subjects were instructed to sustain the Japanese vowel /a/ and to keep the pitch constant. Subjects' speech was frequency modulated using sinusoids ranging from 2Hz to 7Hz and fed back diotically via a headphone. The modulation depth was 200 cents peak to peak. The results indicated that there was a phase-locking effect in the fundamental frequency of produced speech. In the second experiment, a correlation analysis using a pseudorandom signal as a modulation source revealed that the reaction to fundamental frequency perturbation is corrective and that its latency ranges from 100ms to 200ms. Its relation to the auditory-laryngeal reflex will also be discussed.