Interactions of pairs of target and context tones based on relative frequency relation and degree of frequency uncertainty

Abstract

Four normal-hearing listeners completed 2IFC sample-discrimination tasks for frequency, in which they judged which of two tone pairs was drawn from the higher of two Gaussian frequency distributions. The center frequencies of the two target distributions were placed at low (400/500 Hz), middle (1128/1410 Hz), or high (3200/4000 Hz) frequency regions. All distributions were equally spaced and equivariant on a logarithmic frequency scale. Pairs of extraneous (to-be-ignored) context tones were added above, flanking, and below the low-, middle-, and high-frequency target regions, respectively. Across conditions, target and context tones used the same frequency regions, but never occupied the same frequency region within condition. Context tones were fixed in frequency, varied between two known frequencies, or were Gaussian distributed. A level jitter was added to derive perceptual weighting functions across stimuli. The results showed little detrimental effect of fixed-frequency context tones, but large individual differences in the effects of known pairs of tones or tones with Gaussian variation. Weighting functions and patterns of frequency interactions among stimuli will be discussed. [Work supported by NIDCD.]