Yamaha developed Digital Sound Field Processing (or DSP as it is called) in 1986 with the goal of recreating real sound fields in the confines of a small listening space. Yamaha engineers and acoustical architects have visited several dozen performance venues around the world and measured the acoustic properties using a computerized system known as "Single Point Quad Miking." This system is an array of four microphones spaced at exactly 50 mm apart that can actually hear the sound field as you would if you were sitting in the audience. When properly set up in the venue, the Single Point Quad Mic system produces an acoustic blueprint of the venue which contains all of the acoustic information about that venue, such as direct sounds, early reflections and subsequent reverberations. Everything about the venue being measured makes it unique--its size and shape, even the materials that cover its walls. All of the acoustic data about the venue is stored in the computer and downloaded to a microprocessor, which is in turn stored in a Yamaha A/V receiver or amplifier. When you select Concert Hall the information stored in the microprocessor is activated and the magic of DSP fills your listening room.