Not sure if any of the audio fx's in VMS will do what you need. However, I have experience with a free application called Audacity that can do it. If the noise is fairly consistent throughout, Audacity could do it. In VMS, you would have to render the audio track (after ungrouping it form the video) to .mp3 or .wav and then open that file in Audacity, remove the background noise, save it back, then add it back to the audio track.

mike_in_nc