Localization interference between free-field signals

Abstract

With headphones, the perceived lateral position of one frequency band (the target) can be affected by the presence of a second band with different interaural parameters (the interferer). This binaural interference persists despite a stimulus onset asynchrony (SOA) from interferer to target of up to 320 ms [L. R. Bernstein and C. Trahiotis, J. Acoust. Soc. Am. 94, 735–742 (1993)]. The current study presented targets and interferers in anechoic space from pairs of speakers chosen from an array of 12. A visual pointer was used to indicate the perceived location of the target. Localization of a sinusoidally amplitude-modulated (SAM) target (carrier = 500 Hz, modulator = 250 Hz) was unaffected by the presence of an SAM interferer (carrier = 4000 Hz). When the target was the higher frequency, however, there were large individual differences, with some listeners showing interference while others did not. Unlike the studies with headphones, when interference was seen a distractor to target SOA of only 40 ms was sufficient to eliminate the interference. [Work supported by a grant from the NIH, NIDCD 00087.]