Please check to see whether your television supports the HDMI-ARC standard and whether the product is connected to your TV from this output. Alternately, you can use a digital optical cable to connect the two devices.
It's also a good idea to check the sound setting on your television (or set-top box). This should be set to PCM or stereo. If the audio signal travels from the set-top box to the product via the television, please make sure that both devices have been correctly configured, or connect the audio signal from the source device to the product directly.
