Disentangling effects of aging and hearing loss on speech perception in different background noises

Speech perception problems are highly prevalent in the adult population, especially in the presence of background noise which is common in daily conversations. This well-known communication problem originates from a combination of factors that are closely intertwined: aging, peripheral hearing loss, temporal processing deficiencies and declining cognition. The extent to which speech perception is degraded depends on the type of background noise as well. Informational maskers are considered confusing and therefore more difficult to deal with than energetic maskers. Amplitude modulated energetic maskers show temporary increases in the signal-to-noise ratio (noise dips) that facilitate speech perception. However, accurate temporal processing is required to achieve release from masking by the presence of noise dips.

This study includes speech identification tasks with three types of background noise: steady-state and amplitude modulated speech weighted noise (energetic maskers) and the International Speech Test Signal (informational masker). Three age groups are included in the study: young (20-30 yrs.), middle-aged (50-60 yrs.) and older adults (70-80 yrs.). In each age group, persons with clinically normal audiometric thresholds as well as persons with peripheral hearing loss are included. All participants passed a cognitive screening to prevent differences in cognition from confounding the results.

This careful participant selection enables us to disentangle the complex interplay of aging and peripheral hearing loss with regard to speech perception abilities. Effects of aging are investigated by comparing speech perception performance across the normal hearing age groups whereas effects of hearing loss are mapped by examining the normal hearing and hearing impaired age-matched adults. We examine to what extent effects of aging and hearing loss differ in the three types of background noise. In addition, we investigate release from masking. By this, we gain insight into the temporal processing efficiency of the different subgroups and whether this auditory processing ability is related the speech perception performance in the different types of background noise.