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Detection and discrimination of monaural and binaural increments and decrements of intensity with a temporal fringe

Mark A. Stellmack, Neal F. Viemeister, and Andrew J. Byrne
Department of Psychology, University of Minnesota, Minneapolis, Minnesota

Detection thresholds are larger for brief monaural intensity increments in long-duration stimuli than for decrements. This experiment assessed the contribution of a decrement in one ear to direction discrimination of an interaural intensity difference (IID), where a brief intensity increment was presented at one ear and an equal-magnitude intensity decrement at the other. In two-interval monaural tasks, thresholds were measured for detection of an increment, a decrement, and discrimination of the two. In single-interval binaural tasks, thresholds were measured for identifying ear of presentation of an increment, a decrement, and for identification of direction of IID achieved by presenting an increment and decrement to opposite ears. In all cases, thresholds were measured for a 5-ms probe segment as a function of its temporal position in a 50-ms stimulus (broadband noise). The major results: (1) Thresholds for discriminating the ear of presentation of a decrement were much larger than those for simply detecting the decrement monaurally; (2) interaural thresholds were slightly better when both increment and decrement were present relative to increment alone. These results indicate that the decrements contributed to binaural discrimination although by themselves the same decrements were detectable but, at best, weakly lateralizable. [Work supported by NIDCD and DC00683.]

      
       Stellmack, M.A., Viemeister, N.F., and Byrne, A.J. (2005). Detection and discrimination of monaural and binaural increments and decrements of intensity with a temporal fringe. Presented at the 150th Meeting of the Acoustical Society of America.

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