I just experienced the same problem with my 9 month old Sony Bravia KDL-40EX500.S/N 1007771 Firmware version 1.506-SM1.001W00A.
Channel 40 (non digital in Canada)now has no sound. The same network signal from a different city on channel 45 is OK. I use (don't laugh) a deep fringe antenna, so no cable or satellite issues (or bills!) It has been that way for two days now and no problem notices from the network, so it is the TV. Channel 40 on an old CRT TV also works fine with sound. There are no settings on the HDTV that could possibly eliminate sound on only one channel. Also, the mute button will not show CC text, even though it is selected.
Anyone with fix suggestions?
Sony Bravia 32EX500. Over the last two days I've had a problem with the sound on just one of my channels (digital tv channel, no issues until this tv). All of the sound will be there, music, background noise etc, except for the voices. It's like the voice track is missing, very strange. Will last half a day and then be ok for a few days. I messed with the cc and that didn't make a difference. The "alternate audio" option isn't available. Anyone had this problem?