Please check following items:

  1. Disconnect and reconnect the audio source. If you have a projector and are using the RF input, disconnect and reconnect the RF cable.
  2. Connect the audio source to a different speaker system, such as headphones or a different TV/ projector and verify if the audio source is the cause of the problem.
  3. Try using a different audio cable to verify that the current one you are using is not faulty.
  4. Connect a different audio source to the monitor/TV and verify if the problem persists.