I just I was stopping the family barge this morning I notice an interference type noise coming from the right front speaker which continued when the engine was turned of and the key removed even allowing enough time for the cars computers to go into sleep mode. I check everything in the door was both working and switched off normally.
With vision of a flat battery I decided to pull the CD player fuse, as the fuse in the fuse box feeds other circuits I pulled the cd player and disconnected it but noise continued.

So off with door panel -- mirror, electric window, speaker all disconnected but I can still hear the noise apparent coming from the speaker which is off the car!

Penny drops noise is coming from the door pocket underneath an accumulation of bolts, screwdrivers and other junk I find an electric shaver buzzing away.

Lol! I jacked up my Jeep last month and tracked a suspension knock to a pair of welly boots in the passenger footwell!

You see we know too much and not enough at the same time

Another good reason to have a beard

DOH! !!