Impact of age versus hearing loss on amplitude modulation frequency selectivity and speech intelligibility

The perception of amplitude modulations (AMs), which is characterized by a frequency-selective process in the modulation domain, is considered critical for speech intelligibility. Previous studies have provided evidence of an age-related decline in AM frequency selectivity, as well as a notable sharpening of AM tuning associated with hearing loss, possibly due to a perceptual advantage resulting from peripheral compression loss. This study aimed to examine whether speech intelligibility in noisy environments would support the following ideas: i) age-related declines in AM tuning might lead to poorer speech intelligibility, and ii) sharper AM tuning associated with hearing loss would not result in improved speech intelligibility. Young (n=10, 22-28 years) and older listeners with normal hearing (n=9, 57–77 years) as well as older listeners with hearing impairment (n=9, 64-77 years) were included in the investigation. All participants had previously taken part in studies on AM frequency selectivity. Speech intelligibility was tested in various listening conditions, including stationary, fluctuating, and competing-speech maskers. Consistent with the hypothesis, the results revealed an age-related increase in speech reception thresholds, with an additional negative impact of hearing loss. These findings motivate further exploration of the relationship between AM frequency selectivity and speech intelligibility in noisy environments.