An audio engineer explains NPR’s signature sound
> Another thing for engineers or anybody at a station to do is to go into the studio, turn the microphone on, crank it to 11. Don’t talk — so you don’t blow your ears out — and listen to the sounds of all the fans that you have in the room. This is one challenge that we’ve had for decades here. You’re never going to get it to zero. You’re never going to get it completely silent. Nor do you really want to, because in order to get it silent you’ve got to move a lot of equipment out, and there’s a lot of cost with that.Makes me wonder why they don't record the sound of the fans and then invert that audio track and mix it with the mic channel before broadcasting the master channel so that the relatively periodic noise of the fan cancels itself out.