Head movements and sound localization

Abstract

Most research on auditory localization has been conducted with listeners motionless. Nine experiments were conducted to investigate whether and how head motion assists sound localization. In three preliminary experiments, fairly unconstrained responding was made possible by using a partial spherical screen to obscure sources in the left lateral horizontal plane (HP) and the upper-left lateral vertical plane (LVP). The signal was 2-kHz low-pass noise, which thus offered no high-frequency pinna-based spectral cues. As expected, listeners were unable to localize the low-pass noise if they remained motionless throughout the duration of the signal. With a 3-s signal, it was observed that listeners achieved much greater accuracy in terms of front-back discrimination and elevation judgement, if they were permitted to move naturally or if they employed head rotation, about a vertical axis. Following these preliminary experiments, the test equipment was upgraded, so that all regions of auditory space were equally likely to contain sound sources. ... Some remarks are made, in conclusion, about the functions and bases for sound localization in everyday listening conditions.