has anyone ever been awake for a really long time (like between 24 and 48 hours or more), and started to get the impression that they hear music? like a kind of random progression of tones, almost like choral-sounding, or a low whistling, or chimes? if not, I hear this is a great way to give yourself a blood clot.
I couldn't say whether this is entirely the product of imagination, or a combination of that and insomniac chemistry: but this is what I imagine when I read about the music of the Ainur filling the halls of Eru, and passing beyond hearing, like the music of the spheres. you imagine nature to have this unpredictable "rhythm", something that if you heard it might not sound exactly melodic, but the idea that nature itself could be founded on it is a fascinating one...
if the Elves were to tap into this neverending rhythm for magical effect (and I wouldn't underestimate any effect that could be achieved in this way, as it could potentially channel the raw creative powers of the Valar themselves), they are perhaps in a position where they could weave the "music" of nature in with the music of the spirit, which humans have more of an ear for.
the spell of Luthien, for instance, has to be one of the most powerfully moving things a person can hear - that is, distinctly melodic - and her charisma is probably as much a factor there as the song itself; but if it also has a haunting quality, this could owe to an element of fundamental randomness (e.g. dissonance) as well - like a siren's song, which is exactly how I would have described that uh... hallucination
sooner or later there'll be an example (need to find my recorder - am not a musician)