Effects of bandwidth on auditory localization with a noise masker

Although high-frequency content is known to be critically important for the accurate location of isolated sounds, relatively little is known about the importance of high-frequency spectral content for the localization of sounds in the presence of a masker. In this experiment, listeners were asked to identify the location of a pulsed-noise target in the presence of a randomly located continuous noise masker. Both the target and masker were low-pass filtered at one of eight cutoff frequencies ranging from 1 to 16 kHz, and the signal-to-noise ratio was varied from -12 to +12 dB. The results confirm the importance of high frequencies for the localization of isolated sounds, and show that high-frequency content remains critical in cases where the target sound is masked by a spatially separated masker. In fact, when two sources of the same level are randomly located in space, these results show that a decrease in stimulus bandwidth from 16 to 12 kHz might result in a 30% increase in overall localization error.