Check the following: * The audio source (such as TV, HiFi or PC) is not muted * The audio signal for the transmitter is high enough; to increase the audio signal, slowly increase the volume level of the audio source (such as TV, HiFi or PC) * If the above does not help, try to switch to another transmission channel on transmitter Note: Make sure the channel on the headphone is also switched. This can be done by: * If the headphone is equipped with a manual tuning channel switch, switch to the correct transmission channel corresponds with the transmitter * If the headphone is equipped with an AUTO-TUNING BUTTON, press and hold the button for about 1 second and the headphone will automatically tune to the correct transmission channel