I've posted that already in this thread -> http://forums.windowscentral.com/windows-phone-8-1-preview-developers/275540-2.htm
but anyhow I will again write it here:
since i'm using WP8.1, I realised, that if I open a chat in whatsapp, my speaker in the phone (Lumia620) is making a noice like you have no signal in a FM radio station.
it's hearable until I close whatsapp.
the next time I open whatsapp, the sound appears again.
Any idea?
Ditto