Thursday, October 25, 2007

Alan Blumlein: Inventing Stereo Sound

(This is an archived post from our old blog.)

Alan Blumlein invented a lot of things. Here's a list of his patents. from Dora Media Productions' website where there's also information about Robert Charles Alexander's excellent book about Alan Blumlein.

The book is titled The Inventor of Stereo/The Life and Works of Alan Dower Blumlein and you can order it here.

Alan Blumlein had a lot to do with the fact that most home hifi setups have two speakers. The story goes something like: Alan takes his wife to a movie where he puts together the idea that the sound should follow the actors across the screen. Alan called the idea "Binaural Sound". (We now think of "binaural sound" as a recording specially recorded for listening through headphones... I believe Western Electric coined the term "stereophonic".)

Alan Blumlein described a method of recording sound using two microphones with figure-of-eight patterns arranged at 90 degree angles and a method of playing back the resulting audio using two loudspeakers. If Mr. Blumlein were alive today, I would ask him if he intended for recordings made with the Blumlein Technique to be played back with the speakers placed 90 degrees to each other.

Here's a nice description of how the mics are set up with Blumlein Technique.

According to Chesky Records, all of their recordings are made using Blumlein Technique.

In the early days of stereo recording, some engineers (possibly including Harvey Fletcher at Bell Labs) favored three-channel recordings, but I would guess the eventual dominance of the phonograph record pushed things to favor two-channel recordings.

Here's the Patent Specification for Blumlein's directional sound recording technique (also from Dora Music's excellent webpage.) Note that it's from 1931!

Alan Blumlein also did significant work at EMI on H2S Radar. Sadly, Alan Blumlein was killed in the crash of a Handley Page Halifax aircraft (pictured below) that was involved in H2S Radar tests.

It's amazing that Blumlein was granted 128 patents, especially considering that he died just short of his fortieth birthday.

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