Not to alarm anyone but I have experienced the same sort of things and concluded they are a form of hallucination. In the shower I often think I hear the phone ring or my wife calling for me. I have concluded that the brain tries to organize the random jumbled sounds of water splashing and echoes in the shower stall. From time to time the random forms enough of a pattern that it interprets as a familiar sound. My theory is this is magnified in those with hearing loss as our brains are already working harder to make sense out of what we hear. That's my theory, for what it's worth.
Phonak Audeo SMART IX's RIC