The spatial attributes of stimulus frequency in the median sagittal plane and their role in sound localization

Stimulus cues used to locate sounds in the median sagittal plane were investigated. Listeners first were required to report the location of noise bands 1.0 kHz wide whose center frequencies ranged from 4.0 through 14.0 kHz. It was found that the apparent locations of the stimuli depended on their frequency compositions, not their places of origin. As the center frequency was increased from 4.0 to about 12.0 kHz, the apparent location of the sound moved from in front of the subject to the rear. Then, at center frequencies of around 13.0 kHz, the sounds again appeared to come from the front. The authors infer that different frequency regions within the sound's spectrum possess specific spatial referents along the median sagittal plane. When the bandwidth was increased to 4.0 kHz, listeners could locate the stimuli with reasonable proficiency only for the sectors of the median sagittal plane that were represented by the spatial referents inherent in the frequency composition of the stimulus. Finally, a stimulus comprising all audible frequencies above 4.0 kHz could be located proficiently, and it is concluded that this sound, unlike the others, contained all spatial referents for the median sagittal plane, hence the superior performance on the localization task.