Audio–vocal responses of vocal fundamental frequency and formant during sustained vowel vocalizations in different noises

Abstract

Sustained vocalizations of vowels [a], [i], and syllable [mə] were collected in twenty normal-hearing individuals. On vocalizations, five conditions of different audio–vocal feedback were introduced separately to the speakers including no masking, wearing supra-aural headphones only, speech-noise masking, high-pass noise masking, and broad-band-noise masking. Power spectral analysis of vocal fundamental frequency (F0) was used to evaluate the modulations of F0 and linear-predictive-coding was used to acquire first two formants. The results showed that while the formant frequencies were not significantly shifted, low-frequency modulations (<3 Hz) of F0 significantly increased with reduced audio–vocal feedback across speech sounds and were significantly correlated with auditory awareness of speakers' own voices. For sustained speech production, the motor speech controls on F0 may depend on a feedback mechanism while articulation should rely more on a feedforward mechanism. Power spectral analysis of F0 might be applied to evaluate audio–vocal control for various hearing and neurological disorders in the future.