In a news release, Facebook said it’s going to start automatically playing sound on videos when the volume on your mobile device is turned on.
The sound will fade in and out as you scroll through videos in your News Feed.
Facebook has decided to slowly bring this feature to more people after positive feedback during a testing phase, so not everyone is going to have this capability quite yet.
Don’t want videos to automatically play with sound? Set your phone to silent and it won’t happen.