Hello, i currently own a Lumia 820 running WP 8.1 and when i open any conversation in whatsapp there is humming sound continuously played, i found out when i was sitting in complete silence. Is anyone else going through this issue? Please try hearing it with OPEN CONVERSATION and take speaker near your ear cause it's too low to hear from distant. Comment below if you have it too. It's annoying and maybe drains out battery faster? They should give an update. I want to make sure am i the only one? ugh!