Effects of interaural decorrelation and acoustic spectrum on detecting the motion of an auditory target

The ability to detect the motion of an auditory target based on dynamic changes in interaural time differences was measured as a function of interaural correlation and acoustic spectrum in a single-interval forced-choice design. Three subjects listened to headphone-presented noise containing a dynamic linear change in interaural delay (500 μs/s). The stimulus spectrum was broadband (0.1 to 10 kHz), highpass above 1.5 kHz, or lowpass below 1.2 kHz, and interaural correlation ranged from 0.1 to 1.0. Subject performance was nearly identical for the broadband and lowpass conditions, with near perfect detection for interaural correlations of 0.5 or greater, and above threshold (d′ > 1) detection for a correlation of 0.3. Performance was near random when the correlation was 0.1. In the highpass condition, performance rapidly deteriorated from substantially above threshold (d′ > 2) to random level as interaural correlation was reduced from 1.0 to 0.7. This rapid decline in performance at high frequencies may be explained in terms of interaural envelope decorrelation. The text was submitted by the authors in English.