Increased listening effort and decreased speech perception at high presentation sound levels in older hearing-impaired adult listeners.

The sounds we experience in our everyday communication can vary greatly depending on the environment. Paradoxically, increasing the sound level may lead to worse speech perception, especially in noise. This decline is known as "rollover." It is unclear how rollover is experienced differentially across aging groups, as well as for those with and without hearing loss. In addition, there is mounting evidence that listening effort plays an important role in challenging listening conditions and can be directly quantified with objective measures such as pupil dilation. To investigate the interacting effects of temporality, sound level, background noise, and effort on perception, we assessed word identification at multiple levels and in quiet and in noise, in younger (≤25 years) and older (>50 years) listeners without or with mild-to-moderate hearing loss. Pupillometry was used to assess listening effort during these measurements. Behavioral results demonstrated that rollover occurred for both temporal and non-temporal speech contrasts. Rollover occurred in older normal-hearing and older hearing-impaired listeners when speech was presented in background noise. Pupillometry results demonstrated that listening effort was modulated by sound level and that greater listening effort was expended primarily in the presence of background noise. The effect of increased sound level on listening effort was exacerbated by age and hearing loss, with the greatest effect in older listeners with hearing loss. The age- and hearing-dependent effects of rollover highlight the potential negative impact of amplification of high sound levels and therefore has implications for effective treatment of age-related hearing loss.