Had my windscreen replaced today and used the opportunity to try and stop that damn metallic ringing noise that sporadically starts and stops. I'm have had this issue with both my GTI and R and it's driving me insane.
First thing on note, it is categorically the sound actuator rattling. If you gently tap the metal which holds the device, you can hear a metallic tap.
I tried various pads and other things to bolster the device to no avail, it feels like the metal is to thin to support the device.
So, I have removed the sound actuator completely (weight saving bro!) and hey presto, completely buzz free!