Removing Hiss from MP3

[villenuv27]

I extracted audio from a couple of concert DVDs I had purchased, and copied the audio tracks by chapter to my hard drive in MP3 format. Most of the time the quality is very good, and I can burn the tracks to a CD and listen to the audio tracks just as they sound on the DVD. However, sometimes wjhen the tracks are copied to my local drive, they have a slight hissing sound in the background. It's not real prominent, just a bit annoying. Any ideas on how to get rid of the hiss?