Sound goes out and comes back on

If this is a pair of wireless speakers hit the button in the back of the speakers to change the channel. if it is the speakers inside the set, it could be a loose solder connection that heats up after a while and then the solder seperates preventing sound. this same issue could happen to the final amp in the tv, when they get bad they will heat up and stop working. All requiring a tech to troubleshoot the problem.