ABSTRACT
This study examined the ability of listeners to lateralize 753-Hz targets on the basis of interaural differences of level (IDLs) in the presence of a distractor component (253, 353, 553, 953, 1253, 1753, and 2753 Hz) that also contained an IDL. The durations of the two-tone complexes were 200 ms. The IDLs of the target and distractor ranged from -7 to + 7 dB in 1.5-dB steps, with each combination of target and distractor IDLs presented once in a block of 100 trials. Relative target weights were computed from the slopes of the best linear boundaries between left and right responses. Two of the four listeners gave more weight to the target than the distractor when the frequency separation (Af) was large. The other two listeners weighted the target and distractor equally when A/ was large. Three of the four listeners showed a low-frequency dominance when the target and distractor were within a few hundred Hertz of one another, such that the lower frequency was weighted more heavily regardless of whether it was assigned the role of the target or distractor. The fact that a high-frequency dominance has been reported for judgments based on interaural differences of time (Dye, 1993) indicates that the mechanisms underlying spectral asymmetries in binaural processing are likely to be central rather then peripheral in origin.
