Just started having this issue today and I found a fix in the settings. I went into settings from the home screen – to system - to advanced system settings, - to factory reset – then click reset TV audio/picture settings and followed the instructions. Not sure if this is a permanent fix.
Thank you, thank you, FoodGuy. That corrected the problem! My TV was only 6 months old and tonight it started buzzing. By switching cables, connecting thru stereo receiver, etc., the problem remained, so I knew that the issue was in the TV's audio electronics. Turn off "leveling"! Thank You
I found what seems to be a fix for the distorted sound problem. I read somewhere that turning off the volume mode might help. I had mine set to “leveling”, but after I turned it off, I haven’t had any problems with distorted sound.