Maybe I'm weird, but I have a very real auditory experience of music playing in my head. I'm never confused whether I'm imagining it, but it has nearly the same fidelity as hearing with my ears.
I can't conjure up smell/taste experiences the same way, but I do have a sort of hollow visualization ability.
Edit: I read a few more comments, and it seems I'm not alone! Now I wonder whether this is common in the general population or just HN.
I agree with your description, but having the same fidelity is still very different from actually hearing it (having an auditory hallucination). Visualization being more hollow than auditory imagination makes sense because of the much higher bandwidth of visual information.
My impression is that individual differences lie much less in the actual mental abilities than in how people interpret and describe those abilities.
I can't conjure up smell/taste experiences the same way, but I do have a sort of hollow visualization ability.
Edit: I read a few more comments, and it seems I'm not alone! Now I wonder whether this is common in the general population or just HN.