ASA 127th Meeting M.I.T. 1994 June 6-10

3aPP12. Directional masking: Detection, localization, and confidence in responses to a target signal presented in directional noise.

Kim S. Abouchacra

U.S. Army Res. Lab., Human Res. and Eng. Directorate, Aberdeen Proving Ground, MD 21005-5425

Tomasz R. Letowski

Penn State Univ., University Park, PA 16802

The purpose of this investigation was to explore auditory spatial hearing perception in environments containing directional noise. For 40 normal hearing subjects, detection thresholds were measured for a target signal that was spatially separated from directional noise (65 dBA) by either 0(degrees), 45(degrees), 135(degrees), or 180(degrees) azimuth. Following these measurements, localization accuracy and confidence ratings were determined for the target signal presented in directional noise at 0 dB SL, 6 dB SL, 12 dB SL, and 18 dB SL. As expected, detection results showed that as the spatial separation between the target signal and noise source increased, the target signal was more easily detected, with maximum improvements amounting to as much as 13 dB. As sensation level increased, localization accuracy improved and confidence in localization responses increased. Unlike detection, the extent of improvement in localization performance depended more on the spatial location of the target signal than on the amount of spatial separation between the target and directional noise. A general description of detection data, followed by a detailed description of localization and confidence data will be presented and discussed. [Work supported by the U.S. Army Research Laboratory.]