Can listener strategies counter the effect of noise on disordered speech?

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Previous research has found reduced speech intelligibility across voice disorders, including dysphonia and alaryngeal speech. Treatments generally focus on the speaker, such as encouraging clear speech or a slower rate, with little attention to the listener.

This study had three aims: to examine the effect of background noise on the intelligibility of disordered speech, whether perceptual-learning strategies provided to listeners improve intelligibility, and whether subjective voice quality ratings can predict intelligibility. Researchers recorded sentences from 12 speakers: 2 typical speakers, 3 alaryngeal speakers, and 7 speakers with dysphonia. The sentences were assigned to three signal-to-noise ratio conditions—quiet, +5 dB SNR, and 0 dB SNR—and presented individually to 129 healthy listeners, who were divided into control, acknowledgment-of-disorder, and cognitive-perceptual-strategy groups. Speech intelligibility was assessed using orthographic transcription. Three expert listeners also gave subjective voice quality ratings for all speakers.

Listeners made significantly more intelligibility errors as background noise increased (p < .001), while providing strategies did not result in a statistically significant improvement, F(6, 486) = 1.53, p = .17, η2p = 0.02. Regression analysis showed that overall severity in the subjective voice quality ratings predicted speech intelligibility in the noisy condition (0 dB SNR), accounting for 37% of the variance, R² = .365, F(1, 10) = 5.759, p = .037. The researchers concluded that increased background noise adversely affects the intelligibility of people with a voice disorder, but that providing listeners with strategies was not successful in improving it. The findings did support subjective voice quality ratings as a potential index of speech intelligibility.