Linda, rfi is not a standard check that is done on implant equipment. It
requires somewhat specialized equipment so has probably not been done.
I've written to the auditory list at mcGill and we'll see if they have any
ideas.
Tom
Tom Brennan KD5VIJ, CCC-A/SLP
web page http://titan.sfasu.edu/~g_brennantg/sonicpage.html