Why is mentally reproducing music so hard to control? How can it be counteracted? I started decreasing the amount of music I listened to before and especially after I started meditating so that I had to cope less with replaying music passages and enjoy a clearer and more silent mind. Even though now I do not actively listen any more music, sometimes I happen to hear some passages from a TV, a radio or randomly on the Internet, and on certain occasions, while sitting or doing some work, it happens that a certain "mental process" starts reproducing music fragments that I've been exposed to, or that for some reason - for example, through a synesthetic "link" - I've recollected from the past.

I would like to receive some suggestions, and even some observations based on what fields like neurology, psychology etc. offer when relevant, on how to silence my mind when it tries to reproduce fragments of music automatically.

This question originates from a personal need, but I think that it could apply more generally even to other circumstances and for other people. When several months ago I was trying to weaken this automatic habit of reproducing music in my head, I remember I had to apply myself with perseverance for several days, and that the kind of noise from music seemed unusually stronger than any other I had experienced before.
When we sit, we pass through different phases of consciousness.  At first our mind is active and discursive.  It ruminates over all manner of things, rehearses events to come, and rehashes those that have past.  As we move towards stillness - which can be done simply by sitting quietly in one place - our mind settles into a more passive state.  Rather than taking an active role in the creation of our thoughts, our mind relaxes, revealing its deeper layers.  At this point, things may begin to spring up unbidden.  Sometimes we can experience memories from long ago, other times we may see fragments of pictures in our minds, and sometimes we may experience traces of emotion that have no obvious cause.  If you spend any amount of time listening to music, recollection of song is also exceedingly common.

Don't worry about about the music.  If you persist in your sitting, it will begin to fade.  Song is just a different kind of thought.  Treat it like you would any other - let it have its space, don't try to chase it down or drown it out, sit still, and do your best to maintain attention on your breath.