Identification and localization of concurrent speech signals in an auditory dual task

Abstract

In Air Force operations, there is often a competing demand for auditory attention: listeners must identify and repeat a critical message, while also detecting and localizing the presence of a threat. Previous research (Iyer et al., 2014) has shown significant dual task interference, so that the ability of listeners to maintain a high level of performance on a primary task (keyword identification) was offset by decreased performance in a secondary task (critical call sign detection), relative to the respective single-task performances. The current experiment was designed to examine dual-task performance when the secondary task was changed from detection to localization. Listeners identified color-number keywords originating at 0o azimuth (primary task), while they localized the presence of a critical call sign originating from one of thirty-two locations surrounding them in 360° on the horizontal plane. The difficulty of the primary task was varied by employing an N-back task (0, 1, or 2) to increase memory load. Results indicated that the cost of dividing attention between the two tasks increased as the memory load in the primary task increased from 1-back to 2-back. More interestingly, while localization accuracy was unaffected, listeners’ ability to recognize the critical call sign degraded significantly as the difficulty of the primary task increased. The results have important implications for spatial auditory displays in multitalker environments.