Dorrough Audio and Video Metering: Dorrough Electronics designs and manufactures precision audio and video monitoring devices. For the past 20 years, Dorrough has pioneered new technologies in audio signal processing, and monitoring for the broadcast, motion picture, and recording industries. Although having developed and marketed the first Discriminate Audio Processor (DAP) in 1973 (shown at the right), the company is best known for its award winning Audio Loudness Monitors in widespread use throughout the motion picture, recording, and broadcast industries worldwide.