After the latest patch, the audio is completely broken. In any match, after 10 seconds or minute of play, the sound is completely disabled not only in Battlefield, but also in Windows. When exiting the game, the sound in Windows returns.
There has not been a huge outcry of this issue, so it's very likely something on your end - perhaps something that changed without you knowing. Make sure all your drivers (and BIOS) are up to date. Unfortunately, I've had to revert a driver or two in the past for other games to work.
