Duration discrimination in listeners with cochlear hearing loss: effects of stimulus type and frequency.

This study examined the effects of cochlear hearing loss on the ability to discriminate increments in the duration of a stimulus under conditions where the frequency and/or amplitude of the stimulus change dynamically. Three stimulus types were used: pure tones, frequency-modulated tones, and narrow bands of noise. The carrier/center frequency of each 250-ms stimulus either remained constant at 1035 Hz or varied randomly from presentation to presentation across the frequency range 432-2804 Hz. Two groups of listeners participated: 9 with bilateral cochlear hearing loss and 7 with normal hearing sensitivity. The results showed no differences in performance between the 2 groups. However, both groups showed poorer duration discrimination for the conditions where the carrier/center frequency changed randomly than for the conditions where the carrier/center frequency remained constant. In addition, performance was poorer for the narrowband noise stimuli than for the tonal stimuli. This pattern of results suggests that across-frequency temporal judgments are more difficult than isofrequency temporal judgments, but that cochlear hearing loss does not exacerbate this difficulty per se.