Word Intelligibility Versus Angular Relations between Talker and Listener
P. O. Thompson, John C. Webster · The Journal of the Acoustical Society of America · 1962
Two word-intelligibility experiments were conducted under free-field conditions to determine how intelligibility depends upon the distance and angle between the talker and a group of listeners. The talker stood at the apex of a quarter pie-shaped section of listeners. In the course of experiment 1, the talker faced the center radial of listeners (0°), then rotated away from the center in 15° steps to 90°, and finally faced 135° and 180° . The listeners in both experiments either faced the talker's position (0°) or faced away from the talker's position through angles of 15°, 30°, 45°, 60°, 75°, or 90°. The results showed that speech intelligibility was quite uniform over a 90° horizontal arc centered on the speech axis, and that intelligibility was increased slightly when the listening angle was between 15° and 75° in azimuth as compared to 0°.