Multiple sound source localization when sounds are stationary or rotating

Abstract

In the field of spatial hearing, it is known that the sound source localization error increases when distractors are present. This study first determined the maximum number of sound sources that can be perceived. In one experiment, listeners determined how many sources (loudspeakers) presented sounds and these loudspeaker locations. In another experiment, listeners were asked to locate a new sound source which was added to an existing set of fixed sources. Listeners determined up to about four sources producing simultaneous unrelated speech sounds in both experiments. A second part of the research examined the effect of rotating the sound sources on the listener’s perception. If multiple unrelated sounds such as speech rotated, listeners could much more easily determine sound rotation than if the sounds were related to each other. If the sounds were related (e.g., all sounds were harmonics of a fundamental) but were still presented from a number of different loudspeakers, listeners could hardly process the individual sounds even when sounds rotated among the loudspeakers. Thus, the ability to locate multiple sound sources depends on the total number and motion of sources and the type of sound. [Research supported by an AFOSR grant.]