I came across a very annoying problem with my Bose QC3 headphones. There was an occasional static noise from the right cup, regardless of whether I had the phones plugged into anything. I searched everywhere and found no solution. I found a post on a different site with apparently the same problem "Feedback sound like wind noise in right headphone of QC3, starts quietly and gradually gains in strength. Sometimes disappears, then comes back again. No sign of moisture in battery compartment.", but again no solution. Well I discovered the solution myself and think it is worth sharing...

Remove the foam on the earcup giving you problems. It snaps right off, (see video on youtube). Underneath you will find a metal square-shaped piece covering the speaker. There is in fact a small cylindrical object between this piece and the speaker that is making contact!!!!! You need to bend the metal piece outward slightly by applying pressure to the edges, thereby causing it to avoid contact. Once you can see air between metal piece and cylindrical piece, you're done. Pop the foam back on and enjoy!!!!!!!!