What's the latest on localization with two cochlear implants (BiLatCI)?
Some studies indicated that 30% of bilaterally implanted children could not do left-right discrimination at all a 20 degrees or less discrimination. There is some research that indicates that some individuals can develop better acuities with intense practice. The data on left-right discrimination with bilateral implants is rather poor. Correct discrimination seemed to be about 50-70% in clinical testing at best. And these results are from tests done in ideal situation - not in extremely complex outdoor environments. Errors of up to to 30 degrees are typical in accuracy.
To determine if sounds are coming in front or from behind, the ear incorporates the pinna effect (the outer ear structure).
Sound delivered to the audio system without the pinna and not in the frontal horizontal plane can be expected to have far worse results.
"Front-back" discrimination may be not much more than better-than-chance; current systems are not designed for sound localization for front-back and up/down-dimensions tasks.
According to a doctor of audiology familiar with deaf-blind travelers: "Localization is impossible because of the lack of distance hearing. Consider that hearing sound 'acoustically' involves the brain learning that sound nearer has more energy than sound from far away, that there are changes in frequency over distance because high frequencies travel faster than low, etc. The brain learns to interpret these cues. Cochlear implant users are not hearing acoustically, they hear electronically, and therefore the natural change in sound over distances is not apparent."
We need further research and better technologies.
Deaf-blind travelers, their stakeholders, and O&M specialists need to understand the impact of CIs upon O&M tasks and travel.