The localization of non-individualized virtual sounds by hearing impaired listeners

Although many studies have evaluated the performance of virtual audio displays with normal hearing listeners, very little information is available on the effect that hearing loss has on the localization of virtual sounds. In this study, normal hearing (NH) and hearing impaired (HI) listeners were asked to localize noise stimuli with short (250 ms), medium (1000 ms), and long (4000 ms) durations both in the free field and with a non-individualized head-tracked virtual audio display. The results show that the HI listeners localized sounds less accurately than the NH listeners, and that both groups consistently localized virtual sounds less accurately than free-field sounds. These results indicate that HI listeners are sensitive to individual differences in head related transfer functions (HRTFs), which means that they might have difficulty using auditory display systems that rely on generic HRTFs to control the apparent locations of virtual sounds. However, the results also reveal a high correlation between free-field and virtual localization performance in the HI listeners. This suggests that it may be feasible to use non-individualized virtual audio display systems to predict the auditory localization performance of HI listeners in clinical environments where free-field speaker arrays are not available.