Minimum audible angle thresholds obtained under conditions in which the precedence effect is assumed to operate.
Two experiments were conducted to examine the ability of human listeners to localize the "lag" or "echo" source in a precedence effect paradigm. A 5-ms noise burst was presented from a source located between 554-279 cm from the subject. This "lead" source was always located at 0 degrees azimuth. At the same time, one of two sources located at a distance of 610 cm from the subject was also activated with the same 5-ms noise burst. The subject's task was to identify which lag source had been active. Across sessions, the angular distance between the lag sources was varied, so as to allow a determination of the minimum audible angle (MAA) that could be resolved. Tests were run in a room designed to minimize reflections and in a hallway that was acoustically quite complex. No systematic differences in MAA thresholds were observed as a function of the environment employed. MAA thresholds obtained without the signal from the lead speaker were less than 1 degree for four of the five subjects tested. The precedence effect, as measured by the change in the MAA threshold, appears to have only a modest influence on localization performance. Under conditions in which the lead source was concurrently active, the thresholds were generally elevated by only 2 degrees-4 degrees. A reduction of this magnitude in the ability to resolve the position of the lag source does not seem to be sufficient, in itself, to account for the excellent localization performance frequently observed in reflective environments.
Perrott
D R
DR
Psychoacoustics Laboratory, California State University, Los Angeles 90032.
Marlborough
K
K
Merrill
P
P
Strybel
T Z
TZ
D000161:Acoustic Stimulation / Q000379:methods; D001307:Auditory Perception / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D013017:Sound Localization / Q000502:physiology*