The Perception of Lexical Tone and Intonation in Whispered Speech by Mandarin-Speaking Congenital Amusics

Purpose: A fundamental feature of human speech is variation, including the manner of phonation, as exemplified in the case of whispered speech. In this study, we employed whispered speech to examine an unresolved issue about congenital amusia, a neurodevelopmental disorder of musical pitch processing, which also affects speech pitch processing such as lexical tone and intonation perception. The controversy concerns whether amusia is a pitch-processing disorder or can affect speech processing beyond pitch.

Method: We examined lexical tone and intonation recognition in 19 Mandarin-speaking amusics and 19 matched controls in phonated and whispered speech, where fundamental frequency (fo) information is either present or absent.

Results: The results revealed that the performance of congenital amusics was inferior to that of controls in lexical tone identification in both phonated and whispered speech. These impairments were also detected in identifying intonation (statements/questions) in phonated and whispered modes. Across the experiments, regression models revealed that fo and non-fo (duration, intensity, and formant frequency) acoustic cues predicted tone and intonation recognition in phonated speech, whereas non-fo cues predicted tone and intonation recognition in whispered speech. There were significant differences between amusics and controls in the use of both fo and non-fo cues.

Conclusion: The results provided the first evidence that the impairments of amusics in lexical tone and intonation identification prevail into whispered speech and support the hypothesis that the deficits of amusia extend beyond pitch processing.