Disabling UAC Sound Prompt on Windows 8
Something with UAC must have changed between Windows 7 and Windows 8. If you happen to constantly use applications that request elevated privileges while logged on as administrator, you may start hearing a fancy new sound which may drive you crazy. The link below will show you how to simply turn off that sound notification (or to change it to that pleasant new Office notification sound).
Read more here – http://www.windows8library.com/management/disabling-uacs-sound-prompt/