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

Abstract

Purpose: This study aims to investigate the effects of dysphonic voices on speech intelligibility in Cantonese-speaking adults. Method: Speech recordings from three dysphonic speakers and three vocally healthy speakers were presented to 30 listeners with normal hearing (15 males and 15 females; mean age = 22.7 years) in six noise conditions: signal-to-noise ratio (SNR) -10, SNR -5, SNR 0, SNR +5, SNR +10 and quiet. The speech recordings comprised of five different sentence lengths: 5-syllable, 8-syllable, 10-syllable, 12-syllable and 15-syllable. The effects of speaker’s voice quality, noise conditions and sentence lengths on speech intelligibility were examined. Speech intelligibility scores were taken by the listeners’ verbal reporting of the syllables heard and were calculated as the percentage of correctly identified syllables. Results: The speech intelligibility scores of both dysphonic and healthy voices reduced significantly with the increase of background noise. Dysphonic voice was significantly more negatively affected by background noise as compared with healthy voice in SNR -10, SNR -5 and SNR 0 conditions. Sentence length was a significant factor on speech intelligibility under background noise. Conclusion: Speech presented with a dysphonic voice is more difficult to be perceived under background noise when compared to speech presented with a healthy voice. The findings raise the importance of educating the public the impacts of background noise on speech intelligibility and the possible compensatory strategies to minimize the impacts.