Dan Dugan is generally acknowledged to be the first theatre sound designer credited by a Regional Repertory Theatre in North America. He also invented the automatic microphone mixer, the patent to which he licensed for many years to Altec Lansing and which is now manufactured by himself in a much improved and modern version. Wikipedia
The definitive Wikipedia entry for Dan Dugan. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Dan_Dugan