Impaired noise adaptation contributes to the speech intelligibility problems of people with hearing loss

Abstract Understanding speech in noisy settings is harder for hearing-impaired (HI) than for normal-hearing (NH) people, even when speech is audible. This is often attributed to the hearing loss altering the neural encoding of temporal and/or spectral speech cues. Here, we investigated whether it may also be due to an impaired ability to adapt to the background noise. For 25 adult hearing-aid users with sensorineural hearing loss, speech reception thresholds (SRTs) were measured for natural and tone-vocoded words embedded in speech shaped noise (SSN). Stimuli were preceded or not by a 1-second adapting SSN precursor. Adaptation was calculated as the SRT difference between the two precursor conditions. Corresponding data for 28 NH listeners were taken from a previously published study. SRTs were worse for HI listeners, confirming that hearing loss diminishes access to speech acoustic cues. Furthermore, noise adaptation was negatively correlated with the age-controlled hearing loss both for natural (rho=-0.29, N=38, p=0.078) and vocoded (rho=-0.38, N=38, p=0.019) words. Impaired adaptation contributed up to 10% to the SRT loss of HI listeners. We conclude that HI listeners suffer from poorer speech in noise recognition not only because of their impaired access to speech acoustic cues but also because they are less able to adapt to the background noise.