Each time you empty the Recycle bin the system prompt you with a sound alert, to disable this:
- Click the Start button.
- In the search field, type mmsys.cpl and press the Enter key.
- In the window that appears, go to the Sounds tab.
- In the Program list search for "Empty recycle bin" and select it
- Down in the "Sound menu" select "None"
- Validate with the OK button