EFFECTS OF SENSORINEURAL HEARING-LOSS ON INTERAURAL DISCRIMINATION AND VIRTUAL LOCALIZATION

Cross-frequency binaural processing was investigated in listeners with normal hearing (NH) and with bilateral high-frequency sensorineural h earing impairment (IH). In experiment 1 just-noticeable-differences fo r interaural time and interaural intensity were measured using 1/3-oct ave narrow-band noises (NBNs) centered at 0.5 and 4 kHz. These stimuli were presented in isolation and in different cross-frequency interaur al combinations. IH Listeners displayed the best interaural time discr imination when the 0.5-kHz NBN was dichotic and the best intensity dis crimination when both bands were dichotic. Both NH listeners (time) an d Mi listeners (time and intensity) displayed the poorest interaural d iscrimination when the NBNs were presented simultaneously with interau ral differences in only the 4-kHz NBN (0.5 kHz NBN diotic). Localizati on accuracy was measured in experiment 2 using the 0.5- and 4-kHz NBNs in isolation and with 0.5-kHz target/4-kHz interferer and 4-kHz targe t/0.5-kHz interferer conditions. Best localization of NH and IH subjec ts was seen for the 0.5-kHz target, with or without an interferer. Poo rest localization of IH subjects was observed for the 4-kHz target and 0.5-kHz interferer. Results suggest that for these IH subjects, local ization is most difficult when they are forced to rely on interaural i nformation in a higher-frequency region with conflicting interaural in formation at low frequencies. (C) 1998 Acoustical Society of America.