Noises on vehicles drive me nuts. My most recent two noises that I fixed:
In a certain RPM range a high pitched wizzing sound kicks in. Sounded like a key flapping against the frame in the wind. Well, in my driveway I spent about a total of 30 minutes (spread out over like 6-7 days) revving the engine to that RPM until I found what was making the noise: the headlight LED bulb connector was banging around the headlight housing. I taped it up to pad it, but eventually just ziptied it to the bulb and now the noise is gone.
Second noise came after I put on an aftermarket gas tank. Turns out it was hitting the frame just a touch. This took a couple of tries, but eventually I padded the lower attachment point for the gas tank until it stopped. New gas tank is nice: makes the bike look a little bigger and I get an extra gallon of fuel.
tl;dr: noises suck. I was lucky that they were vibration caused, not wind caused, as they are easier to find. Glad you found yours.