Have you tried listening to chiptune, MIDI, or electronica music? I am congenitally hearing-impaired myself and also enjoyed Vocaloid, although I had never wondered about a connection before. I've sometimes thought that when Vocaloid producers don't try for realism but go for simpler easier 'purer' Vocaloid voices, it sounded like chiptune/MIDI/electronic. So those might be an interesting musical control group.