An update - since my original post, after being initially rather strict about keeping the radio turned off, I've become a bit more moderate now. I still think that the ideal
is to stop intentionally putting musical ideas in to my mind, but when I try to totally
abstain from all music at present, it ends up feeling like 'pushing myself too far'. So I'm disentangling myself from non-Dhammic music gradually
instead. Between two pieces of music, I choose the one that is the more
soothing, wholesome or peaceful, upon consideration; and above all if I sense it's a 'sticky' piece of music I turn it off right away.
By bringing in whatever sati and panna I can, I also ask sometimes: why do I feel the need to put the radio on anyway? Why isn't 'just driving' enough?' (Or 'just washing dishes' - these are the two instances where I am most likely to turn music on). I take a look at the mind that is bored, seeking distraction from 'the mundane'. I challenge myself sometimes to make more of an effort, and to just pay closer attention to the task at hand,
and stop being so greedy for entertainment (which is really discontent, laziness and aversion manifesting, imo).
Earworms are manifesting less often now, but when they do, I do agree that it's better to not get aversive about them. After all, that would just multiply the defilements even more. I note the music in my head, note any irritation I might have with it, and try to move on to the task at hand - whatever that may be.
As for my long-term aspiration, well yes ultimately if we want to get in to deep enough samadhi to be able to break through delusion, then not just mental
but also some physical
seclusion from distracting sense objects is not only going to be helpful, but from my reading of the suttas, is actually recommended and prescribed by the Buddha himself:
"Endowed with this noble aggregate of virtue, this noble restraint over the sense faculties, this noble mindfulness and alertness, and this noble contentment, he seeks out a secluded dwelling: a forest, the shade of a tree, a mountain, a glen, a hillside cave, a charnel ground, a jungle grove, the open air, a heap of straw. After his meal, returning from his alms round, he sits down, crosses his legs, holds his body erect, and brings mindfulness to the fore.
An adept might well be able to practice anywhere at all, but as far as general guidelines go, the places mentioned above are all where you would reasonably expect to be alone and undisturbed by other people, for a while anyway. They are *more likely* to be places where one will find some peace and quiet. So although I can not live that lifestyle perfectly at present, it would be best to move gradually in that direction,
gradually giving up whatever is an obstacle for samma samadhi; and intentionally turning on music that is unconnected with Dhamma, or is sensually stimulating and not peaceful - is that not obviously unskilful, in an ultimate sense? So when and as I'm ready, I'll let go of it, gradually. I don't think I'm being extreme about this.
Thanks to all for their replies, interest and advice thus far.