I bought a Galaxy S3 last night. This morning I was getting a random notification sound (and sometimes LED) about once an hour. I would check the notification bar, but it's always empty. Even weirder, I've changed my default notification sound in Android as well as the notification sound in GMail, Messenger, Facebook, etc. to something different, but this one keeps playing the default whistle that comes on the Sprint S3 when you first purchase it. As of this evening, it's now happening about 3-4 times an hour. I've been googling this for the last hour and everyone seems to point to the Yahoo Mail app. But I don't have that installed on my phone, so that's out of the question. A few other people seem to have this problem without the Yahoo Mail app, but every thread has gone unanswered. Nobody seems to know where this is coming from. Also, this has been happening on my girlfriends Galaxy Nexus for the last 3-4 months but maybe only once a day. I'm completely lost and I can't even sleep with my phone in the room because it's going off even with the phone on silent.