Perhaps we are accustomed to work learning or entertainment, the backstage open QQ or other chat software, are also accustomed to their familiar to the message tone. Remember that when Windows7 first came on the market, many people wondered why other audio and video playback software would suddenly turn down when chatting software was in the news. In fact, this is the Windows7 of the human nature of the place.
If you are accustomed to the sound of news, or the sound of the message is necessary for you, then, under the "Communication" tab of "Playback Device", "when Windows detects communications activity," Select "Do not perform any action", so that the background chat software to information, will not affect the wonderful songs or wonderful movies.
If you really don't want to be bothered by boring messages, you can turn on the volume synthesizer, where Windows7 will now assemble all the applications with sound output, which can be targeted for muted or volume adjustments. If you like listening to music, then the browser and QQ are set to mute, concentrate on your music world.
This feature of Windows7 is very user-friendly, without affecting the sound output of other applications, it is convenient for other programs to control sound, rather than simply mute the entire system. If you think this feature is convenient, you can pin it to the taskbar, so you have a own volume control Panel, at any time to adjust the system sound state, work and entertainment two.