My Surface 2 was on my desk and I was visiting my regular websites when suddenly a loud sound, like radio static, started coming through the speakers. The sound will stop occasionally but is on more than off and seems to happen no matter whether I am on the Start screen or using an app. I thought at first might be associated with when data is transmitted through wifi but I'm not sure. I have tried restarting and turning wifi on and off to no effect. The sound is not affected by volume control or mute. It is really loud, like the speakers are at full volume. Any suggestions?