Since I have no personal experience with cochlear implants, I can provide only an opinion (however it is a somewhat informed opinion).
Though a cochlear implant can dramatically improve the hearing ability of an individual, it still has an external "removable" portion that contains a speech processor, transmitter and battery. If the external device is not in place the implant does not work. When a screening audiogram is done, hearing aids and other assistive devices are to be removed, thus the audiogram would be the same as if it had been done prior to implant surgery.
As an aside, and only because I've been accused of being pedantic, I make the following comments. A category of "H4" is not by ear, it is a single category based on the auditory capacity of both ears. Also, you would (if you could) not be joining the Air Force. The only legal military organization in Canada is the "Canadian Armed Forces", There is a "command" within that organization that is called the "RCAF" and is predominantly manned by individuals that wear an "air force (i.e. light blue)" uniform, however there are also plenty of members wearing the other two uniform colours serving in that command. The two occupations that you mention are both "purple". That means that they can be employed in support of any of the environmental commands. You may request a particular colour uniform as part of the enrolment process and it may be granted but it is not guaranteed and, even if it was, a PAO or TDO wearing an air force uniform could just as easily end up serving on an Army or Navy base or at a location that is not affiliated with any of the environmental commands.
