The hard way, if you have the skill, is to replace the speakers.  The bad news is that this probable won't fix it as it is likely that it is internal noise causing the distortion.

there is an easy solution that will probable work.  Using the audio output connection you could hook it up to a stereo system or boom box and use those for sound.   the only thing technical is making sute your cord has the right connectors/adapters on each end.  take a picutre or a good look at both devices audio connectors (output on the TV, input on the Stereo/boombox) and the salesman at your local electronics store should be able to help you find just what you need.
at a guess you will likely need an RCA female to RCA female cord or an RCA to stereo mini male.

hope this helps.

Long_Knight