Evacuation system utilizing the precedence effect

Abstract

This study aims at building an evacuation system using audio signals. The feature of the system is the utilization of the precedence effect for a listener to easily perceive the direction of an emergency exit. Two kinds of pre-listening tests were conducted to reconfirm the basic characteristics of the precedence effect which needed consideration in the proposed system. Firstly, the influence of various kinds of background sounds to the precedence effect was investigated in a horizontal plane. The complexity of signal, that is, the difference in levels between the audio signal and background sound, and the variety of the sounds, influenced the precedence effect. Secondly, the generation and disappearance of the precedence effect were investigated in the vertical plane. We confirmed that the generation and disappearance of the precedence effect were clear in the horizontal plane and vague in the vertical plane. The results of the two pre-listening tests led us a new concept of an evacuation system with the loudspeakers set beside a wall in a passageway. In the listening tests of the proposed system, the generation and disappearance of the precedence effect of an audio signal were investigated. The configuration of the loudspeaker setting had a good effect on guidance of evacuees during an emergency. The installation angle of a loudspeaker was shown to be an important factor in the perception of stable sound localization in the direction of the emergency exit. At installation angles of 10 or 20°, the direction of sound localization became more straight ahead than in the case of other installation angles. Furthermore, at the worst listening position for the perception of sound localization, we confirmed that the difference in intensity between the loudspeakers contributed to the improvement of sound localization. Therefore, using loudspeakers with sharper directivity was suggested, which can easily improve the direction of sound localization at the worst listening position to become more straight ahead. We confirmed that the proposed evacuation system with loudspeakers set beside the wall in a passageway was a promising candidate.