Hi,
You may follow these steps to disable or turn off keyboard sound:
a. Click on the Start button, and then click on Control Panel. In the search box, type sound, and then click Sound.
b. To change one sound, click the Sounds tab, and then click on default beep and at the bottom in sounds choose none and click on apply and OK.
c. Close sound and check if the beep sound disables.
For your reference have a look at the link:
http://windows.microsoft.com/en-us/windows7/Change-computer-sounds