Someone who hears via use of a cochlear implant is considered a pike'ach and not a cheresh, halachically. See this MY question for details.
My question focuses more on the actual workings of the implant. This web site says:
A cochlear implant is very different from a hearing aid. Hearing aids amplify sounds so they may be detected by damaged ears. Cochlear implants bypass damaged portions of the ear and directly stimulate the auditory nerve. Signals generated by the implant are sent by way of the auditory nerve to the brain, which recognizes the signals as sound. Hearing through a cochlear implant is different from normal hearing and takes time to learn or relearn. However, it allows many people to recognize warning signals, understand other sounds in the environment, and understand speech in person or over the telephone.
There is a rule that one does not fulfill his obligation of hearing the shofar sound unless he is, in fact, hearing the original sound of the shofar and not an amplified sound or an echo.
I'm uncertain if the sound heard via implants would be considered an "original" sound or not, and if that would, thus. qualify a wearer to fulfill the mitzvah of hearing shofar.