Interaction of interaural time and intensity

Abstract

The thresholds for interaural temporal and intensive differences were determined as a function of a variety of stimulus conditions. The thresholds were determined in a two-alternative, forced-choice task when the stimuli were presented with a constant interaural temporal or intensive difference. That is, the thresholds were measured in conditions in which the lateral image is moved off midline with the introduction of an interaural temporal or intensive difference. A random change in overall level prevented the listener from using monaural intensive or binaural loudness differences as cues for discrimination. The thresholds were measured as a function of signal frequency (200–1200 Hz) for 250-ms tones presented at 60 dB SPL. Both interaural temporal and intensive thresholds increased as the value of the constant interaural difference increased (images moved away from midline). The interaural temporal difference threshold changed from approximately 3° to approximately 18° as the constant interaural intensive difference increased from 0 to 15 dB. The interaural intensive threshold changed from approximately 1 to approximately 2.1 dB as the constant interaural temporal difference changed from 0° to 180°. The effects of frequency were small but significant. The results will be discussed in terms of the relationship between lateralization and localization of pure tones. [Work supported by The National Science Foundation.]