Loud Buzzing during commercials

Question

Hi - I have a Mitsubishi TV about 7 years old with cable - I have had cable in to fix the very loud buzzing that occurs mostly (99%) during the commercials. Time Warner has been unsuccessful so far and one guy advised that maybe I needed some gadget to filter out whatever is causing the interference however, I need to know what that gadget could be. Any thoughts on this would be greatly appreciated.
Regards,
Gladys Masiello
Staten Island, NY