This may be a feature or a bug...depends on your point of view. When I'm using multiple audio applications with Mumble voice chat client, say a game and Audacious, the volume of the game and Audacious halves when someone speaks on Mumble. Now this might be valuable in some situations. Alternatively it may also be valuable to reduce music and game sound when I key the Mumble push-to-talk and activate my microphone. However, I mostly have no need for my music volume being reduced every time some speaks in Mumble.
If this is a new feature, congratulations well done, how can I toggle it on and off, or turn it off permanently. If it is a bug how can we go about trying to fix it.
Linux Mint 14 'Nadia' x64 Cinnamon and MATE (it turns out).
This is actually a Mumble feature and they must have enable it by default in the latest version. There is indeed a simple switch to control this in Configure | Settings | Audio Output | Attenuate applications by... | while other talk or while you talk. Which is great...unless you don't know about it.