An experimental hybrid cochlear implant is proving helpful to patients who have partial hearing loss. There are nine medical centers in the US approved to try the hybrid as part of a study, and so far, the results are encouraging. People who can't hear high frequencies, but still can hear low frequencies are not good candidates for the traditional cochlear implants or hearing aids, but can benefit from the hybrid model which works like a typical implant. It is worn outside the ear and converts sounds into electric signals.