Age-related differences in the temporal modulation transfer function with pure-tone carriers

Abstract

Detection of amplitude modulation (AM) in 500- and 4000-Hz tonal carriers was measured as a function of modulation frequency from younger and older adults with normal hearing through 4000 Hz. The modulation frequency above which sensitivity to AM increased (“transition frequency”) was similar for both groups. Temporal modulation transfer function shapes showed significant age-related differences. For younger subjects, AM detection thresholds were generally constant for low modulation frequencies. For a higher carrier frequency, AM detection thresholds then increased as modulation frequency further increased until the transition frequency. In contrast, AM detection for older subjects continuously increased with increasing modulation frequency, indicating an age-related decline in temporal resolution for faster envelope fluctuations. Significant age-related differences were observed whenever AM detection was dependent on temporal cues. For modulation frequencies above the transition frequency, age-related differences were larger for the lower frequency carrier (where both temporal and spectral cues were available) than for the higher frequency carrier (where AM detection was primarily dependent on spectral cues). These results are consistent with a general age-related decline in the synchronization of neural responses to both the carrier waveform and envelope fluctuation.

Optimizing pulse-spreading harmonic complexes to minimize intrinsic modulations after auditory filtering

“…This shape and position compare well to observations reported by others, who measured TMTFs with a sine-wave carrier at 4 kHz at similar modulation rates, equivalent presentation levels, and comparable listener groups (Yost and Sheft, 1997;He et al, 2008;Vinay and Moore, 2010). Studies reporting better thresholds (Viemeister, 1979;Kohlrausch et al, 2000;Moore and Glasberg, 2001;Stellmack et al, 2005) presented stimuli at higher levels, improving the detection of modulations imposed on sine-wave carriers (Kohlrausch, 1993).…”

Spectrotemporal modulation sensitivity for hearing-impaired listeners: Dependence on carrier center frequency and the relationship to speech intelligibility

“…The fact that these correlations were observed for the higher tested temporal modulation rate of 32 Hz suggests an influence of age on temporal modulation processing, consistent with previous findings (e.g., He et al, 2008). Significant correlations between age and STM sensitivity were not observed for any conditions where the HI listeners showed poorer STM sensitivity than the NH listeners, nor for any low temporal modulation rate conditions for which TFS cues might play a role.…”

“…This is likely related to a loss of the compressive gain of the cochlear active mechanism, whereby impaired listeners do not receive a benefit of larger gain applied to a low-level signal that immediately follows a higher-level masker (Nelson et al, 2001). Temporal resolution has also been shown to be negatively impacted by age, with older listeners with nearnormal audiograms nevertheless demonstrating reduced temporal modulation sensitivity (e.g., He et al, 2008). Reduced temporal resolution could disrupt speech reception by smearing the temporal features present in the speech signal or by increasing the effects of forward masking.…”

Cortical and Sensory Causes of Individual Differences in Selective Attention Ability Among Listeners With Normal Hearing Thresholds

“…These anatomical results support the idea that aging alone can produce hidden hearing loss. Consistent with this, older human listeners with NHTs often have temporal processing deficits (see Fitzgibbons & Gordon-Salant, 2010a, 2010bHe, Mills, Ahlstrom, & Dubno, 2008;Purcell, John, Schneider, & Picton, 2004;Snell & Frisina, 2000;Snell, Mapes, Hickman, & Frisina, 2002). Thus, not only is it likely that cochlear synaptopathy causes communication difficulties in younger adults but it is also likely that the prevalence of the cochlear synaptopathy increases with age.…”