Quadraphonic Sound

Quadraphonic sound uses four channels to output sound; right front, left front, right rear, and left rear. The goal of a quadraphonic sound system is to reproduce sounds in both the front and back of the listener, which simulates 360-degree sound. Quadraphonic sound became the more common and popular choice in the late 1950s to early 1960s versus Four Channel Discrete which was also available during that time.