Effects of the body and eye-position conditions for sound localization in the frontal vertical plane

In order to investigate the effect of posture on sound source localization in daily 3D spatial listening, we performed a sound source localization test in the front-middle (vertical) plane. This test systematically controlled the subject´s body angle and the relative position between the eye level and the center of the sound source position. The test was conducted for three eye-positional conditions, i.e., EL (eye level was lower than the center of sound sources), EC (eye level was the same as the center of sound sources), and EH (eye level was higher than the center of sound sources). For each condition, five postures were tested at angles of 90deg, 67.5deg, 45deg, 22.5deg, and 0deg. The results showed that the average correct response rates for the EC condition were higher at the 90deg and 0deg postures than at the 67.5deg, 45deg, and 22.5deg postures; however, these differences decreased in the EL and EH conditions. In all eye-positional conditions, the localization of the source position tended to be distorted (skewed) toward the eye level of the subjects and not toward the center of the loudspeaker.