Most likely you have a software based tuner which does software-encoding. If that's the case, then you should connect a stereo cable from the audio out of your tuner (if you have one) to audio in of your sound card and then try or you can also try and change your audio settings at http://mycast.orb.com > Open Application > Control Panel > TV/Webcams > Devices > expand the plus sign in front of your detected TV tuner, and try a different Audio Device and Audio Input.

You should also make sure to "Uncheck" the MPEG-2 option. Note: Support for software based (Non-MPEG2) tuners are still in beta and not fully supported.