Relation between perceived direction of a sound image and the behavior of the precedence effect

• Published in: Applied acoustics Vol. 74; no. 10; pp. 1122 - 1135
• Main Authors: Harima, Toshio, Shiga, Kenta, Abe, Koji, Takane, Shouichi, Watanabe, Kanji, Sato, Sojun
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2013; Elsevier
• Subjects: Acoustics; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Level difference; Physics; Precedence effect; Public address system; Structural acoustics and vibration; Summing localization; Time difference; Time difference; Level difference; Summing localization; Public address system; Precedence effect; Probability; Perception; Acoustics; Time; Sound source; Experimental study; Localization
• ISSN: 0003-682X; 1872-910X
• DOI: 10.1016/j.apacoust.2013.03.012

•Behavior of the precedence effect (PE) and the summing localization (SL) was investigated.•Relation of the PE and/or SL to the sound localization was also investigated.•Subjects and conditions were possibly kept common throughout the above two experiments.•The temporal and directional boundaries separating the PE and the SL were defined.•The directional boundary exists at around 10° inside the directions of sound sources. When similar sounds come to a listener from two different directions with the same level and small time difference (0–2ms), he/she perceives a single sound image and its position changes from the middle of two sound sources for no time difference between two sounds to the direction of the leading sound with increasing time difference. This phenomenon is well known as a change from the summing localization to the precedence effect, but the process for such a change has not been sufficiently elucidated. In order to make use of the precedence effect for designing a public address system, the effect needs to be quantified. In this paper, we describe two hearing experiments carried out with the same subjects and conditions. We then analyzed the relation between the perception of a sound image and the behavior of the summing localization and the precedence effect. The difference between two experiments was in the instruction that the subjects were asked to answer. The instruction in the first experiment was the perceived direction of the sound image, while in the second experiment the instruction was the position of the sound source nearest to the perceived sound image. The boundary time difference separating the summing localization from the localization based on the precedence effect was calculated from the results of both experiments. Consequently we found that: (a) the absolute value of the boundary time difference varies in the range of 0.4–0.8ms with the small level difference (0,+3dB) between two sound sources and (b) the perceived image at the boundary time difference is localized around 10° from the left/right-side sound source to the middle of two sound sources.