Even if you mute your system, certain events will still trigger the system beep. To suppress these system-level beeps, perform the following steps:
Start a registry editor (e.g., regedit.exe).
Navigate to the HKEY_CURRENT_USERControl PanelSound subkey.
Double-click Beep, set the value to “no”, and click OK.
Close the registry editor.
Log off and log on for the change to take effect.