Do you not hear music in your head? Like I have a song running through my mind right now, lyrics and all. No visuals just the music. If you don’t hear a voice in your head wouldn’t that mean you can’t ever hear music in your head either?
Other person here: I can only hear realistic sounds and visualize realistic images when I'm in a half-asleep state or in dreams. Otherwise it's very blunt. For example I cannot realistically hear music in my mind, I can imagine myself humming it though (and my vocal muscles ever so slightly tense up if I do), and I can imagine myself speaking in the same way, but it's mostly a very faint thing, and is mostly about imagined movement of my mouth etc., rather than sound. E.g. imagine clapping your hands as a motoric action, but imagine them in your hand, not the visual of it, but imagine what it would feel like in your arms and hands. It's a bit going in that direction with my imagined speech.