Dan's Blackbox Project #1 - Spring 2010 - From Stereo to Ambisonics

Two Englishmen, both with a knack for mathematics and audio yet who lived a generation apart, contributed significantly to the way we hear surround sound today.

Alan Blumlein was born in 1903. The story goes that at the age of seven he repaired a doorbell at the family home and presented a bill to his father, signed "Alan Blumlein, Electrical Engineer." Blumlein garnered some 128 patents over his lifetime.

"Stereo" was not a term used by Blumlein, rather he called it "binaural sound." After watching a "talkie" at a movie house with his wife, he told her that he had developed a way for the sound to follow the actor across the screen. Movies of that day, and for many more years, only had one point of sound origination, that being from the single speaker behind the screen. Blumlein received a patent for the "use of a coincident pair of velocity microphones with their axes at right angles to each other." This arrangement is used in recording today and in his honor called the "Blumlein pair."

Among his other patent claims are the methods to record stereo to record in a single groove and the stereo disc recording head. Alan Blumlein was a key developer of an airborne radar system and died in the crash of a test flight in 1942.

Michael Gerzon was born in 1945 and researched axiomatic quantum theory at Oxford. He was quite involved in sound recording and was a contributor the to field of the psychoacoustics of surround sound, the human perception of the sounds around us. He became an independent professional audio consultant. He was an active writer who could convey his thoughts on the theoretical level of the Journal of the Audio Engineering Society and on the application and explanation level of Hi-Fi News and Wireless World.

Gerzon grew up in the era when stereo became a commercial reality as a replacement for monophonic recording and reproduction. He also witnessed the commercial disaster of quadraphonic sound, when multiple incompatible formats turned consumers away from the market. Gerzon and his Oxford friend Peter Craven expanded Blumlein's theory of the coincident pair of velocity microphones and went on to invent the Soundfield microphone, a microphone containing four cardioid microphone capsules which will record surround sound not only in the horizontal field of Blumlein's theory, but in spherical (360-degree) surround sound.

Michael Gerzon died in 1996 from complications from asthma.