I am on the side that this isn’t semantics and is a real phenomenon. For me, I can hear in my mind very well. I can hear so well that I can occasionally confuse things I’ve hear in my mind’s ear for a real sound (did you just say something?). It very slightly crosses the line into an auditory hallucination. I can hear music so well that I don’t need a radio to listen, just think of the first few seconds of a song and off it goes on the jukebox.

My mental images are nowhere near this clear, but they are a kind of “darksight” a seeing and a not seeing, ephemeral but also real and useful for visualization and problem solving.