The bandwidth effect on monaural and binaural localization

Listeners located, monaurally and binaurally, an 8.0 kHz centered noise burst whose bandwidth was set at 2.0, 4.0, 6.0 and 8.0 kHz. Loudspeakers, placed 7.5 degrees apart, covered an arc extending from 15 degrees to 165 degrees to the left of midline. Listeners reported the number of that loudspeaker from which the noise bursts appeared. A significant reduction in localization errors was associated with increments in bandwidth and for binaural localization, this was attained largely through fewer instances of confusing sounds from the front with those from the rear. While overall, binaural accuracy exceeded monaural accuracy when sounds came from the front or rear, no appreciable differences between the two listening conditions were noted when the sounds came from the middle section of the arc. Only when broadband noise was employed, as it was in a supplementary set of observations, did binaural localization uniformly surpass monaural localization in accuracy - a finding attributed to the introduction of low frequencies which resulted in the addition of interaural ongoing phase differences to the constellation of localization cues.