Freehubs going south can be funny too, and they will often make more or less noise in different gears, something about the lateral load. IOW, if it's louder in certain gears than others that would seem to indicate the freehub. If it's constant, probably spokes. From what I have read here, I am leaning towards spokes. When the weather turns, bikes start creaking and popping and generally it's just a nuisance noise, hard to track but easy to remedy.
BL