Sound problem. Sunday I was watching Braves baseball game...all of a sudden the sound went hot

Question

Sunday I was watching Braves baseball game...all of a sudden the sound went hot like in a echo chamber sort of.I tried other channels thinking it was just the transmission from the ball park...but all channels are the same. I took the tv off of the designated cable jack to see if it was the cable lead...but still the same when hooked up to another lead. All other tv's in household are good. I tried adjusting the sound at the OSD but still no change. What now?Thanks for any help you can give me. The Book that came with tv offers no other troubleshooting help.