The Effect of Background Noise on Intelligibility of Dysphonic Speech.

Purpose: The aim of this study is to determine the effect of background noise on the intelligibility of dysphonic speech and to examine the relationship between intelligibility in noise and an acoustic measure of dysphonia: cepstral peak prominence (CPP).

Method: A study of speech perception was conducted using speech samples from 6 adult speakers with typical voice and 6 adult speakers with dysphonia. Speech samples were presented to 30 listeners with typical hearing in 3 noise conditions: quiet, signal-to-noise ratio (SNR)+5, and SNR+0. Intelligibility scores were obtained via orthographic transcription as the percentage of correctly identified words. Speech samples were acoustically analyzed using CPP, and the correlation between the CPP measurements and intelligibility scores was examined.

Results: The intelligibility of both typical and dysphonic speech was reduced as the level of background noise increased. The reduction was significantly greater in dysphonic speech. A strong correlation was noted between CPP and intelligibility score at SNR+0.

Conclusions: Dysphonic speech is relatively harder to understand in the presence of background noise as compared with typical speech. CPP may be a useful predictor of this intelligibility deficit. Future work is needed to confirm these findings with a larger number of speakers and speech materials with known predictability.