I can confirm this buzzing noise is coming from the electric power steering assembly on the steering column. I have only investigated this myself to determining the point of origin. I am a subaru technician and this noise existed on my 13 brz aswell my 15 aozora brz. I did mention the noise to our technical department but I never received an update. I actually forgot about it myself until the 15 when I was completely my break in procedure. Usually i run with some form of audio noise and didnt notice it above that. I will pursue it next week and see if I can come up with my own solution to remedy the noise.
ill get on techlines ass again about it to lol