Fixes interface and addon sounds that do not play while the in game sound effects are disabled.
There's also a system in place to filter unwanted sounds from playing (currently set to filter out the new LFD pulsing sound). There is not yet a UI to edit sound filters, this will be added in the future. Due to API limitations, this filtering can only happen while sound effects are disabled (but that's the whole point of this addon).
Please ensure Enable Sound is checked under System -> Sound. You can then disable Sound Effects, Music, and Ambient Sounds. This will result in only UI sounds (ready check, boss mods, etc) playing.
Background and Details:
With the launch of Cataclysm, Blizzard made a change to the sound API's to allow developers to pick a category for sounds. This channel argument is optional and when it's not included, sounds default to the SFX channel. Any sound played on the SFX channel is muted when in game sound effects are disabled. Previous to this change, all sounds played on whats now known as the MASTER channel. Sounds played on the MASTER channel still play while sound effects are disabled.
Since Blizzard changed the default behavior, any addon that wanted their sounds to play while SFX are disabled required an update. Even to this day, many addons still lack this update, because if you do not play with SFX disabled, you'll never encounter the problem. In addition, the default interface sound effects (including LFG queue, ready check, etc) no longer play with SFX disabled.
This addon changes the default channel back to MASTER, so all addons and interface sounds play like they did before Cataclysm. If an addon does provide the channel information, then MasterChannel will play the sound on the specified channel.
