Effects of target speech distance on auditory spatial attention in noisy environments

When people perceive auditory information in noisy environments, auditory spatial attention plays a major role in extracting target information from multiple sound sources. For auditory spatial attention, the effects of distance have been unclear. In this study, we examined the relationship between auditory spatial attention and the distance to the target speech sound. In an experiment, background multi-talker noise was presented 1 m from the listeners. The target sound or distracting speech sound was presented at one of four distances: 0.13, 0.25, 0.5, or 1 m. By manipulating the probability of the target presentation distance, the listener's attention was implicitly focused at a specific distance. Listeners were asked to respond as soon as the target speech sound was perceived. Experimental results clearly revealed that the listeners showed faster responses to the target speech sound at the focused distance than at other distances. Moreover, the shape of spatial selectivity of auditory spatial attention varied based on the focus distance. These results are expected to reflect the effect of peripersonal space.