Magnitude estimation of perceptual fusion of multiple sound sources

Abstract

The precedence effect states that the first sound wave arriving at a listener has more influence on the perception of location than later arriving echoes. When a source plus echoes is perceived approximately at the location of the source, the image is said to be ‘‘fused.’’ The following set of experiments introduces a new procedure to estimate fusion of clicks. Listeners are presented with a source click plus a single echo click at a variety of delays. Stimuli are rated between a value of ‘‘0’’ and ‘‘100,’’ with ‘‘0’’ indicating a single source and ‘‘100’’ indicating more than one source. These ratings are used to determine delays which are perceived as a single source (receive a rating of ‘‘0’’) and delays which are perceived as multiple sources (receive a rating of ‘‘100’’). These anchor stimuli are then presented on each trial. The stimulus which received a rating of ‘‘0’’ is presented first, followed by the sound to be rated. The stimulus which received a rating of ‘‘100’’ is presented last. This procedure was used to determine fusion as a function of location and number of echoes presented. [Research supported by a program project grant from NIDCD.]