ABSTRACT
It has been suggested that virtual auditory displays (VADs) be used to enhance the intelligibility of warnings, advisories, and speech communica tions in noisy environments. It is often assumed that the benefit gained by giving the signals distinct perceptual locations is related to the masking level difference (MLD). This study suggests another possible reason: Signals with distinct locations may be preattentively processed in parallel because audi tory location cues lead the listener to perceptually organize them as separate “objects.” This research investigated auditory display techniques that might enable sonar operators to monitor multiple channels concurrently. On each test trial, short bursts representing underwater events were presented at a rate of either 1 or 2 bursts/s. The subject’s task was to determine whether a previously learned target burst was among those presented and, in some conditions, to also identify the relative location of the target. The bursts were presented at virtual locations based on the full head-related transfer function (“3-D sound” cues), at comparable locations based on interaural time and intensity differences only, diotically with visual location cues, or diotically with no location cues. 3-D sound cues enhanced recognition relative to diotic presentation, but visual and time/intensity cues did not. Because the bursts were relatively widely separated in time, explanations in terms of the MLD seem unlikely. Rate of presentation did not interact with 3-D versus diotic presentation, suggesting that the segregation of sound sources accompanying 3-D sound cues is not based on a limited-capacity mechanism (i.e., focal attention). Contrary to the recognition results, visual cues produced better localization performance than did 3-D sound cues or time/intensity cues. These results suggest that with 3-D sound cues the bursts are perceptually organized as objects and preattentively processed in parallel, whereas with
visual cues they must be serially processed in focal attention. The importance of attentional processes in recognition performance with virtual auditory displays is discussed.
