Does your TV / sound system have any configuration options for the speakers? On PC this problem can be caused by having misconfigured speakers (2.1 headhones set as 5.1 speakers, etc).
Do you have different speakers you can try, if you aren't using internal TV speakers, or does it have an audio jack you can try headphones with?
For external speakers, try disconnecting and reconnecting them, in case there is a loose connection.
What TV / speakers are you using?
