I can imagine these sounds but they don't have any audio texture - no volume, no tone. At the same time, if I imagine a large bell and a small bell ringing then there is a difference but its like reading "BONG!" and "ting" (which for me also has no audio).

Can you sing in your mind? I can represent the words and I can recall the tune so I can represent the words at the correct pace to match the tune but there is no audio so it's a bit like subtitles.

I can imagine them conceptually but not the actual sounds themselves. Same for a song; I can't "hear" a song in my mind but I can imagine it. Hard to explain.