Disentangling the effects of hearing loss and age on amplitude modulation frequency selectivity

Abstract

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.

Investigating the effects of age and hearing loss on speech intelligibility and amplitude modulation frequency selectivity

“…A reduction in AM tuning would likely result in increased AM masking, which could disrupt the intelligibility of the target speech. Additionally, the observed beneficial effects of hearing loss on AM frequency selectivity, as reported by Regev et al (2023b), may also impact speech intelligibility in noisy environments. However, although the increased AM frequency selectivity found in older HI listeners compared to older NH listeners (Regev et al, 2023a(Regev et al, , 2023b) may suggest a decrease in AM masking with hearing loss, it is hypothesized that this would not directly translate into improved speech intelligibility.…”

“…Additionally, the observed beneficial effects of hearing loss on AM frequency selectivity, as reported by Regev et al (2023b), may also impact speech intelligibility in noisy environments. However, although the increased AM frequency selectivity found in older HI listeners compared to older NH listeners (Regev et al, 2023a(Regev et al, , 2023b) may suggest a decrease in AM masking with hearing loss, it is hypothesized that this would not directly translate into improved speech intelligibility. Indeed, the greater AM frequency selectivity in HI listeners is believed, as proposed by Regev et al (2023b), to be linked to reduced cochlear compression, which is known to be connected to various supra-threshold deficits that impair speech intelligibility (e.g., Glasberg and Moore, 1989;Oxenham and Moore, 1997;Moore and Oxenham, 1998;Moore, 2003).…”

“…Regev et al (2023a) found a general reduction in AM frequency selectivity associated with age, resulting in broader masking patterns among older compared to young listeners with normal hearing (NH listeners). Conversely, Regev et al (2023b) demonstrated a general sharpening of masking patterns among young and older listeners with hearing impairment (HI listeners) compared to similarly aged NH listeners. This finding suggested that sensorineural hearing loss was accompanied by a perceptual benefit that partially offset the detrimental effects of age, possibly due to the HI listeners' ability to exploit an increased internal representation of AM depth resulting from reduced peripheral compression when "listening in the dips" of the masker.…”

“…Based on these modeling studies, the spectral decomposition of the stimulus envelope carried out by the modulation filterbank, i.e., AM frequency selectivity, has been suggested as an important factor for accurately predicting SRTs (see Relaño-Iborra and Dau, 2022, for a review of different speech intelligibility models using modulation filtering). Regev et al (2023aRegev et al ( , 2023b investigated the effects of age and hearing loss on the selectivity of hypothetical modulation filters using a perceptual AM masking task. Regev et al (2023a) found a general reduction in AM frequency selectivity associated with age, resulting in broader masking patterns among older compared to young listeners with normal hearing (NH listeners).…”

“…However, although the increased AM frequency selectivity found in older HI listeners compared to older NH listeners (Regev et al, 2023a(Regev et al, , 2023b) may suggest a decrease in AM masking with hearing loss, it is hypothesized that this would not directly translate into improved speech intelligibility. Indeed, the greater AM frequency selectivity in HI listeners is believed, as proposed by Regev et al (2023b), to be linked to reduced cochlear compression, which is known to be connected to various supra-threshold deficits that impair speech intelligibility (e.g., Glasberg and Moore, 1989;Oxenham and Moore, 1997;Moore and Oxenham, 1998;Moore, 2003). Furthermore, the assumption that a sharpening in AM tuning with hearing loss would not lead to an improvement in speech intelligibility is consistent with previous studies showing that HI listeners exhibit higher SRTs than age-matched NH listeners (Goossens et al, 2017).…”