Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. On December 28, 2005, XM Satellite Radio announced that it had teamed up with Neural Audio Corporation to introduce XM HD Surround, XM HD Surround broadcasts XM channels in 5.1 digital surround sound. For a time XM broadcast a variety of special shows and live music performances in this format. According to the press release, Denon, Onkyo, Pioneer Electronics (USA) Inc., and Yamaha will introduce home audio systems capable of playing XM HD Surround in 2006. The 5.1 surround sound is encoded in the stereo wave for transmission and is thus compatible with any mono/stereo/matrix-style receiver. If played on a 5.1 audio set equipped with Neural Surround decoder, the watermarks (i.e. spatial cues) in the waveforms are detected and the signal is recovered to its original 5.1 form.