Sony MDR-DS5100 Dolby Infared Wireless Advanced Headphone System (Silver) (Discontinued by Manufacturer) 5.1ch Digital surround headphone system, Processor + Headphone The Dolby signals are encoded into the infrared wireless signal and decoded by the headphones for an astonishingly realistic 3-Dimensional sound Based on psychoacoustic perceptual science associated with Head Related Transfer Functions (HTRFs) Based on the way that parts of your head obstruct sound, the sound is angled so that your brain perceives that sound is coming from the front, rear, sides and between - creating the sound field of a perfect listening room - with stereo headphones Optical Digital input