I bought a refurbished NES four years ago, and have very recently begun to have audio problems. I am using an original RF adapter, and have the console connected directly to my TV (not through a VCR or other device). The console is set to ch 3, as is my TV. I have a game in the console and hit the power button. The picture quality and game play is fine. However, the sound is distored; by distored, I mean that I can only hear loud static and voices/music from a TV channel, even the picture is clear and the game play fine. The audio of the games (music, sound effects) is not audible at all. Is this a problem with the RF adapter?  Could it be a problem with the console itself? Any information or suggestions would be appreciated. Thank you.

I dug up some A/V cables and used them to connect the NES to my TV.  Video and audio are now crisp and clear!  Apparently, it is the RF adapter and not the console, which is good news.  Problem has been solved!