How to disable sound in certain applications?

I hate it when games sometimes play music while being installed.

Is there an easy way to ban selected applications from outputting sound on Windows 7?

From Windows Vista onwards, you can use the Volume Mixer application (double-click on the volume icon in the system tray) to control the sound level of individual applications.

Here's a sample screenshot of it:

You can also run the program by typing sndvol from the Run prompt.

It should work for what you would like to do.

Windows 7 - in the System Tray, double click on the Sound icon and then click Mixer. You should then see a list of your running apps. Click on the speaker icon for the individual app to disable sound.