Mallika Chadaga

In this study, listeners localized a target in isolation and in the presence of a distractor. The target consisted of ten 10-ms Gaussian pulses (energy between 3-5 kHz) while the distractor was either a 100- or 400-ms narrowband (1-2 kHz) noise burst. The listener, with head unrestrained, was seated in the center of a sound booth with 36 loudspeakers spaced every 10 degrees on the horizontal plane and obscured by screens. On each trial, the target was played through a randomly selected loudspeaker. Listeners used a laser pointer to indicate their perception of the target location. Infrared cameras detected the position of the pointer and calculated its response angle. In separate conditions, the distractor played from either a fixed or randomized speaker across trials. Certain trials observed the additional parameter of varying target-to-distractor onset synchrony. Results indicate that the left-right component of responses was essentially unaffected by the presence of the distractor in any condition. With notable inter-subject variability, the front-back response component also showed little effect of the distractor. This absence of consistent effect of the distractor contrasts with previously reported work. The target and distractor in the present research, however, were generally more discriminable than in past studies, which likely mitigated at least some of the deleterious effect of the distractor on target localization ability.