Automixer
Automixers are frequently employed in settings where it is expected that a live sound operator won't be present, such as courtrooms and city council chambers.
[3] While a skilled mixing engineer can greatly enhance the performance of a sound reinforcement system they cannot anticipate with perfect accuracy which participant will speak next in a spontaneous discussion.
Frank J. Clement and Bell Labs received a patent in 1969 for a multiple-station conference telephone system that switched its output to the loudest input.
Peter W. Tappan and Robert F. Ancha devised a system of seat sensors that would activate one of 350 hidden microphones at the Seventeenth Church of Christ, Scientist in Chicago in 1970.
[11] In 1972, Keith A. T. Knox with the British Post Office Corporation developed an adaptive threshold gate circuit intended for speakerphone usage.
[12] Dan Dugan showed his first Adaptive Threshold Automatic Microphone Mixing System in 1974 at the 49th Audio Engineering Society (AES) meeting in New York,[13] and was granted a patent for a control apparatus for sound reinforcement systems which sensed ambient sound level in the environment of a theater to control each microphone's level.
[20] IRP released the Voice-Matic series of 4 × 1 and 8 × 1 automatic mixers using "Dynamic Threshold Sensing" that weighed a combination of the amplitude and history of the signal to determine channel access.
[21] This master output reduction was the solution used by Yamaha Pro Audio two decades later in their DME series of digital signal processing (DSP) products, incorporating an automixer function which was otherwise an 8- or 16-channel noise gate.
[23] Stephen D. Julstrom of Shure Brothers Incorporated was granted a patent in 1987 for a teleconferencing system that used special directionally gated microphones mixed automatically and sent to a distant party via telephone line.
[25] In 1985 Innovative Electronic Designs (IED) introduced the circuit card frame-based auto mic mixing system featuring combine-separate function and programmable gain control (PGC) modules.
[32] Peavey's Architectural Acoustics division used three levels of hierarchy in their 1998 "Automix 2" product, placing the first- and second-most influentially weighted sources at inputs 1 and 2, respectively.
[34] In 2004, the first standard audio mixer incorporating an eight-channel automixer section was released by Peavey in their Sanctuary Series,[35] and in 2006 the similar HP-W was introduced by Crest.
[36] Both mixers were aimed at the house of worship market, adding functions that ease the process of audio mixing for religious organizations.
In 2007, Mark W. Gilbert and Gregory H. Canfield of Shure (Niles, Illinois) were granted a patent for a digital microphone automixer system that used time of arrival as its main decision-making criteria.
