Lumia 950 :: Ticking / Popping Sound While Locked

I just bought the new Lumia 950, I love it, but recently I am having this Little issue

Some times, when the phone is locked, it will start playing this ticking sound from the back speaker (the one next to the camera). If you listen closely, you can hear the following:

1. The speaker turns on, you can hear static,
2. The speaker turns off abruptly with a "click" sound,
3. The speaker stays off for about 1 second, then starts again from point 1.

This ONLY happens while the phone is locked , and it stops if you unlock the phone. However, once it's started, the only way to stop it is to reboot the phone.