Temporal gap detection in sensorineural and simulated hearing impairments.

The objectives of this study were to assess the effect of the configuration of a hearing loss on gap detection and to determine if hearing impairment affects temporal resolution, per se. The minimum detectable gap duration, MDG, in a low-pass (cut-off at 7 kHz) noise was measured monaurally as a function of sound pressure level in six listeners with normal hearing, seven with hearing impairments of primarily cochlear origin, and eight with impairments simulated by masking. The impaired listeners' MDGs at 80 and 90 dB vary from about 3.5 ms (equal to the normal MDG) to about 8 ms and show little correlation with their average HL. At lower levels, the MDG is enlarged for all impaired listeners owing to the decreased SL of the noise. Most of the enlargement of the MDG could be reproduced by presenting a normal listener with a masking noise spectrally shaped to simulate the impaired listener's audiogram. However, at high levels, some impaired listeners performed worse than their simulated-loss counterparts, indicating that temporal resolution per se may be reduced in some, but not all, impaired listeners.