Comparing sound localization and speech-in-noise in unilateral, bilateral, single-sided deaf, and bimodal cochlear implant users.

Cochlear implant users do not experience spatial hearing with the same accuracy or acuity as typical hearing listeners. Two standard measures of spatial hearing are sound localization error and speech reception thresholds (SRTs) in spatially separated noise. While sound localization requires a complicated setup, SRTs may be measured with fewer loudspeakers and less testing time. If a predictive relationship between sound localization error and SRTs can be measured, then the spatial hearing abilities of cochlear implant users may be quickly assessed by measuring one task or the other. To test this, 12 bilateral, ten single-sided deaf, six bimodal, and five unilaterally implanted listeners were recruited. In general, bilateral users had the smallest localization error and greatest improvement in SRTs between collocated and spatially separated conditions, while unilateral users had the largest localization error and worst SRTs. When unilateral listeners were excluded, localization error was significantly correlated with the difference between spatially separated and collocated SRTs. There was no relationship between sound localization error and raw SRT scores. The spatial hearing of unilateral listeners would benefit from receiving a second implant, and many bimodal users would likely experience a benefit from this intervention as well.