The effects of dysphonic voice on speech intelligibility in Cantonese-speaking adults

Purpose: This study aims to investigate the effects of dysphonic voice on speech intelligibility in Cantonese-speaking adults. Method: Speech recordings from three speakers with dysphonia secondary to phonotrauma and three speakers with healthy voices were presented to 30 healthy listeners (15 men and 15 women; M_age = 22.7 years) under six noise conditions (signal-to-noise ratio [SNR] -10, SNR -5, SNR 0, SNR +5, SNR +10) and quiet conditions. The speech recordings were composed of sentences with five different lengths: five syllables, eight syllables, 10 syllables, 12 syllables, and 15 syllables. The effects of speaker’s voice quality, background noise condition, and sentence length on speech intelligibility were examined. Speech intelligibility scores were calculated based on the listener’s correct judgment of the number of syllables heard as a percentage of the total syllables in each stimulus. Results: Dysphonic voices, as compared to healthy voices, were significantly more affected by background noise. Speech presented with dysphonic voices was significantly less intelligible than speech presented with healthy voices under unfavorable SNR conditions (SNR -10, SNR -5, and SNR 0 conditions). However, there was no sufficient evidence to suggest effects of sentence length on intelligibility, regardless of the speaker’s voice quality or the level of background noise. Conclusions: This study provides empirical data on the impacts of dysphonic voice on speech intelligibility in Cantonese speakers. The findings highlight the importance of educating the public about the impacts of voice quality and background noise on speech intelligibility and the potential of compensatory strategies that specifically address these barriers.