Abstract:

Ten normal-hearing college students performed two-interval, two-alternative, forced choice discrimination tasks designed to determine the optimal range of interstimulus (ISI) intervals for auditory discrimination of intensity, duration, and frequency. Stimuli were randomized (roved) along frequency, intensity, and duration dimensions to reduce monotony and minimize the listener's reliance on a remembered standard. The center frequency was 500 Hz, the center duration was 30 ms, and the center intensity was 75 dB SPL. Differences to be discriminated were from 0.75 to 3.0 dB for intensity, 1.5 to 6 ms for duration, and 7 to 20 Hz for frequency. Interstimulus intervals were studied from 70 ms to 15 s. Maximum discrimination scores were observed in the range of ISIs from 1.0 to 3.0 s, for all three stimulus dimensions. These preliminary findings suggest the operation of a common, dimension-independent, sensory processing mechanism within the central nervous system. [Work supported by NIH and Neuro Logic, Inc.]