The perception of amplitude modulations (AMs) has been characterized by a frequency-selective process in the temporal envelope domain and simulated in computational auditory processing and perception models using a modulation filterbank. Such AM frequency-selective processing has been argued to be critical for the perception of complex sounds, including speech. This study aimed at investigating the effects of age on behavioral AM frequency selectivity in young (n = 11, 22–29 years) versus older (n = 10, 57–77 years) listeners with normal hearing, using a simultaneous AM masking paradigm with a sinusoidal carrier (2.8 kHz), target modulation frequencies of 4, 16, 64, and 128 Hz, and narrowband-noise modulation maskers. A reduction of AM frequency selectivity by a factor of up to 2 was found in the older listeners. While the observed AM selectivity co-varied with the unmasked AM detection sensitivity, the age-related broadening of the masked threshold patterns remained stable even when AM sensitivity was similar across groups for an extended stimulus duration. The results from the present study might provide a valuable basis for further investigations exploring the effects of age and reduced AM frequency selectivity on complex sound perception as well as the interaction of age and hearing impairment on AM processing and perception.

The processing and perception of amplitude modulations (AMs) in the auditory system reflect a frequency-selective process, often described as a modulation filterbank. Previous studies on perceptual AM masking reported similar results for older listeners with hearing impairment (HI) and young listeners with normal hearing (NH), suggesting no effects of age nor hearing loss on AM frequency selectivity. However, recent evidence has shown that age, independently of hearing loss, is detrimental to AM frequency selectivity. Hence, the present study aimed to disentangle the effects of hearing loss and age. A simultaneous AM masking paradigm was employed, utilizing a sinusoidal carrier at 2.8 kHz, narrow-band noise modulation maskers, and target modulation frequencies of 4, 16, 64, and 128 Hz. The results obtained from older (n=10, 63-77 years) and young HI listeners (n=3, 24-30 years) were compared to data from young and older NH listeners. Notably, the HI listeners generally exhibited lower (unmasked) AM detection thresholds and greater AM frequency selectivity compared to their NH counterparts of similar age. These findings suggest that age negatively affects AM frequency selectivity in both NH and HI listeners, while hearing loss improves AM detection and AM selectivity, likely due to the loss of peripheral compression.

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.