up. >> reporter: dr. wilkinson is a lead investigator. children of los angeles and the university of southern california are not the first to be performing auditory brain stem implants. in fact, surgeons in italy have been doing this procedure for more than ten years. but this trial is the only fda approved one in the united states funded by the national institutes of health. >> do you want that? do you want that? >> reporter: they are also focusing on one particular age group. >> we know from cochlear implant studies that the earlier the auditory system in the brain can be stimulated, the better the children will do. in our study we actually have the ages of 2 through 5, so we feel that that's a balance between finding a safe age to do it but also doing it at a young enough age the child will benefit from the device. >> reporter: caden just made the age cutoff, turning 5 one month after his surgery. the operation was a success, but