Front- and rear-facing horizontal sound localization results in adults with unilateral hearing loss and normal hearing

Binaural hearing allows listeners to take advantage of auditory cues that are necessary for sound localization. Patients with asymmetric or unilateral hearing loss receive degraded or absent binaural cues and often demonstrate decreased sound localization in the horizontal plane. Given the importance of sound localization for everyday function, there is a need for clinically feasible methods to evaluate localization, particularly as validation of intervention for patients with unilateral hearing loss. The present study compared sound localization results obtained for front-facing and rear-facing soundfield systems and for a rear-facing head related transfer function (HRTF) system in two hearing groups, listeners with normal hearing and those with unilateral hearing loss. Results between the three systems were highly correlated and repeatable. Neither age nor a pure-tone average of 0.5, 1, 2 and 4 kHz correlated with localization performance among normal hearing participants. Among the UHL group, age and onset of severe to profound hearing loss were positively correlated with localization results; length of deafness was negatively correlated. Behavioral chance performance was established for localization with rear-facing HRTF and rear-facing soundfield test systems; group mean results for unilateral hearing loss participants were significantly better than chance. Continued work is needed in developing clinically feasible evaluation methods for patients with asymmetric or unilateral hearing loss, particularly as the effects of treatment options are assessed.