Is my Mate 7 listening to me?! topic

Ive just noticed something strange with my phone. I had it placed flat on my desk and was looking at something with my face close to the screen and I can hear a very faint buzzing, like whwn a radio is on but the volume is turned down to zero. It seems to come on and off randomly....

The sound only happens when the phone is on a flat surface and you have to really listen out for it in a silent room.

Any idea what this is? I do have bluetooth and wifi turned on...