These materials are for educational purposes only. No copyright infringement intended. Sing-a-long with the Stars Multiplex (MPX) Karaoke Collection contains both the backing tracks (left channel) and the vocal guide (right channel). This will help you to easily learn the version of you favorite singers. For a better appreciation, use stereo headphones or players. When you are ready to sing on your own, just switch the balance knob to the LEFT and enjoy singing. If you have any questions or suggestions, please feel free to leave your comments.