ABSTRACT
See also Reverberation; Surround Sound HOWARD FERSTLER
Used in some home-based surround-sound processors, it basically involves removing outof-phase information from a two-channel soundtrack and converting it for use in the surround channels. In the early 1960s, David Hafler developed one of the original extraction systems, a passive, unamplified hookup for a group of four loudspeakers hooked up to a two-channel amplifier, which steered out-of-phase components in a stereo recording to a set of rear loudspeakers, which were themselves wired to deliver a kind of ersatz stereo effect. This process, called Dynaquad, was marketed as a product by Hafler’s Dynaco company. In the late 1960s, Peter Scheiber, at that time a professional bassoonist, filed a U.S. patent for an encoder/decoder matrix system that would turn out to be a major competing format for quadraphonic sound in the early 1970s. Later, Dolby Laboratories cited many of Scheiber’s patents in the creation of the Dolby surround system.
