Inherent envelope fluctuations in forward maskers: Effects of masker-probe delay for listeners with normal and impaired hearing

Abstract

Forward-masked thresholds increase as the magnitude of inherent masker envelope fluctuations increase for both normal-hearing (NH) and hearing-impaired (HI) adults for a short masker-probe delay (25 ms). The slope of the recovery from forward masking is shallower for HI than for NH listeners due to reduced cochlear nonlinearities. However, effects of hearing loss on additional masking due to inherent envelope fluctuations across masker-probe delays remain unknown. The current study assessed effects of hearing loss on the slope and amount of recovery from forward maskers that varied in inherent envelope fluctuations. Forward-masked thresholds were measured at 2000 and 4000 Hz, for masker-probe delays of 25, 50, and 75 ms, for NH and HI adults. Four maskers at each center frequency varied in inherent envelope fluctuations: Gaussian noise (GN) or low-fluctuation noise (LFN), with 1 or 1/3 equivalent rectangular bandwidths (ERBs). Results suggested that slopes of recovery from forward masking were shallower for HI than for NH listeners regardless of masker fluctuations. Additional masking due to inherent envelope fluctuations was greater for HI than for NH listeners at longer masker-probe delays, suggesting that inherent envelope fluctuations are more disruptive for HI than for NH listeners for a longer time course.

Simultaneous and forward masking of vowels and stop consonants: Effects of age, hearing loss, and spectral shaping

“…In addition, forward masking of consonants extends over longer durations following the noise offset compared to masking for vowels (between 10 and 40 ms). Compared to younger adults, the results from older adults with normal and impaired hearing are consistent with a slower recovery from forward masking as observed for fluctuating forward maskers (Svec et al, 2016). The similarity in performance for older adults with normal and impaired hearing suggests that the broader auditory filters typically associated with cochlear hearing loss do not fully account for reduced vowel identification.…”

“…Forward masking may have reduced perception of the burst following a 40-ms delay for older adults. This observation may be related to slower recovery from forward masking, as observed with fluctuating maskers for older adults with hearing loss (Svec et al, 2016). Identification of the final consonant by older adults was observed with the 100ms delay, indicating that some information from the formant transitions from the vowel into the consonant may be essential for older adults.…”

“…Given that detection of brief signals within a masker is poorer for older than younger adults (Dubno et al, 2002), perception of brief consonant cues may be further limited for older adults with normal and impaired hearing, even with sufficient audibility. In addition, older adults with hearing loss have shallower slopes of recovery from forward masking (Svec et al, 2016). Therefore, we predicted that consonant identification would be poorer than vowel identification for all listeners, and poorer for older adults than younger adults due to poorer detection of brief acoustic cues.…”

Forward Masking of the Speech-Evoked Auditory Brainstem Response

“…This reduced ability to take advantage of the brief low-energy epochs in the masker is due in part to age-related deficits in temporal processing that manifest as increased susceptibility to forward masking. Advanced age is associated with higher forward-masked thresholds (4,5), as well as a greater persistence of forward masking – i.e., slower recovery from prior stimulation (6,7) – as shown using both simple tonal and speech-shaped noise signals. Fogerty et al (8) have demonstrated a complex interplay between age-related deficits in forward masking and the differential vulnerability of subclasses of phonemes to such masking.…”

Inherent envelope fluctuations in forward masking: Effects of age and hearing loss

“…1101/2022 Inherent envelope fluctuations 5 (Neff, 1986). The results of Svec et al (2016) revealed that the binaural cue from a diotic forward masker elicited a reduction in GN disruption at a masker-signal delay of 75 ms for listeners with SNHL. In that study, however, approximately half of the GN disruption was still observed for listeners with SNHL after presenting a binaural cue, suggesting that controlling for listener uncertainty did not account entirely for the magnitude of GN disruption for listeners with SNHL.…”