Detection of temporal gaps in sinusoids by elderly subjects with and without hearing loss

Thresholds for the detection of temporal gaps in sinusoidal signals were measured as a function of frequency (100-2000 Hz) and level in 15 elderly hearing-impaired subjects and 11 elderly subjects with near-normal hearing at frequencies below 2000 Hz. The sinusoids were presented in a background noise intended to mask spectral splatter associated with the gap. In a separate experiment, auditory filter shapes and detection efficiency were estimated for the same subjects using the notched-noise method, at center frequencies of 100, 200, 400, and 800 Hz. The gap thresholds at higher signal levels were similar for the two groups of subjects at all center frequencies tested. The mean gap thresholds were slightly higher than those obtained previously from young normally hearing subjects, but this was mainly due to the results of a few subjects with large gap thresholds; the majority of the elderly subjects had gap thresholds within the normal range. Thus reduced temporal resolution does not seem to be an inevitable consequence of aging. Gap thresholds at low center frequencies tended to be positively correlated with the equivalent rectangular bandwidth (ERB) of the auditory filter, the opposite of what would be expected if the auditory filter played a role in limiting gap detection. Detection efficiency, as estimated from the notched-noise experiment, was poorer for both groups of elderly subjects than for young normal listeners, but detection efficiency was not significantly correlated with gap thresholds.