After landing QQ, Windows7 sounds big and small, how is it going?

Question: Windows 7 Ultimate, after landing QQ, the computer sound began to be wrong, when the song was heard, the voice suddenly became big and small, and did not find any suspicious places for a long time. Changed the QQ music, thousands of listeners and other players are like this, thought it was a QQ problem, changed a few versions of QQ is also the same. Reinstalling the sound card driver can't solve it, how can it be solved?
Answer: Actually, this is not a problem, just because Windows 7 can change the sound size of other programs according to the sound of some programs. So in the sound properties (you can right click on the small speaker icon in the lower right corner of the desktop, click “sound”), and then click on “Synthesizer” to see it. When running communication software such as QQ, msn, Fetion, etc. Once a friend sends a message, or go online or offline, it will help you to weaken the sound of other programs (the default setting is to reduce other sounds by 80%). The volume of each running program can be adjusted as needed.