Intercom apparatus for integrating disparate audio sources for use in light aircraft or similar high noise environments

Intercom apparatus having stereo amplifiers adapted for connection to one or more headsets. A plurality of headset output and microphone input connections are provided. Each microphone input includes a separate microphone switch and audio detector whereby only microphone inputs having voice audio thereon are activated. Stereo entertainment and aircraft radio audio inputs are provided. An aircraft radio audio detector is interfaced, along with the various microphone audio detectors, to entertainment partial mute circuitry whereby the presence of a voice or radio audio signal lowers the amplitude of the entertainment input. Microphone and aircraft radio partial mute circuitry are interfaced through a priority selector switch with respective microphone and radio signal detectors. The priority selector switch is a two position, center off arrangement whereby, in one position, aircraft radio signals partially mute microphone signals and in the second position microphone signals partially mute aircraft radio signals. In the center off position no cross muting occurs and the respective signals sum in conventional manner.