How to increase the volume on TS4's Alert Sounds

["Hango Winspy" <hwinva@xxxxxxxxxxx>]

I can hardly hear the beep when the TS4's Alert Sounds.  In the TS Online 
Manual's Alert Sounds Section stated

Note: If you have a Windows-compatible sound board, you can assign a WAV or 
MOD sound file to the default beep to make the warning sound more 
noticeable.

But I don't know how to implement this instruction.  Any advise from the 
O-List is appreciated.

Regards

Hango