Estimating Cochlear Implant Users' Sound Localization Abilities With Two Loudspeakers.

The ability to tell where sound sources are in space is ecologically important for spatial awareness and communication in multisource environments. While hearing aids and cochlear implants (CIs) can support spatial hearing for some users, this ability is not routinely assessed clinically. The present study compared sound source localization for a 200-ms speech-shaped noise presented using real sources at 18° intervals from -54° to +54° azimuth and virtual sources that were simulated using amplitude panning with sources at -54° and +54°. Participants were 34 adult CI or electric-acoustic stimulation users, including individuals with single-sided deafness or aided acoustic hearing. The pattern of localization errors by participant was broadly similar for real and virtual sources, with some modest differences. For example, the root mean square (RMS) error for these two conditions was correlated at  = .89 ( < .001), with a mean RMS elevation of 3.9° for virtual sources. These results suggest that sound source localization with two-speaker amplitude panning may provide clinically useful information when testing with real sources is infeasible.