iPhone 4S buzzing / static noise

Anyone else experiencing a buzzing / static noise?? You can notice it when on a phone call, but it seems to be coming from the processor or something when using 3G data (a good way of hearing it is listening on the back of the phone while running the speedtest.net app)

Someone has also recorded the sound:

There's quite a few threads on the Apple discussion forums and a whole bunch of people reporting the issue. I'm just wondering if there are people out there with phones that are perfectly fine and I should be attempting to get a replacement, or whether this is a general hardware issue with the design of the phone...

How are everyone else's phone's?