Contribution
Investigating the link between modulation frequency selectivity and age-related speech intelligibility difficulties
* Presenting author
Abstract:
Amplitude modulation (AM) carries important information in speech signals. Therefore, AM frequency selectivity has been suggested as crucial for speech intelligibility. Recent evidence suggests that older listeners with normal hearing exhibit less AM selectivity than younger listeners, which may contribute to age-related speech intelligibility difficulties. This potential link was investigated in young and older listeners with normal hearing. AM selectivity was measured using a complex-tone carrier with a sinusoidal target modulation and noise modulation maskers. Speech-reception thresholds (SRTs) were measured with tone-vocoded speech and maskers with varying AM content. It was hypothesized that older listeners would show higher SRTs than young listeners for modulated maskers as well as a different pattern of SRTs across masker modulation frequencies, due to reduced AM selectivity with age. An age-related reduction of AM selectivity was found. The SRTs did not show a consistent age effect across maskers, although trends suggested a greater susceptibility to AM masking with age. The SRTs also showed that modulated maskers were detrimental to intelligibility irrespective of modulation frequency, in contrast with previous reports of a particular importance of frequencies below 16 Hz. This work motivates further investigations of the role of AM masking and AM selectivity in speech intelligibility.