January 2003 Meeting Presented by Ron Streicher


In 1931, Alan Blumlein was at work in his lab at Electrical Musical Industries (EMI) in London on methods for improving the art of phonograph recordings.  The result of his work was published in his landmark 1933 patent in which he describes a wide array of techniques for stereophonic recording and reproduction, all of which are still in use today:  the process by which the human auditory system can perceive accurate spatial localization from two loudspeakers;  several basic stereo microphone pickup techniques, including the Mid/Side technique and the crossed-figure-of-eight array which bears his name;  methods for creating and playing a stereophonic phonograph record, including the 45/45 cutting system later developed and marketed by Western Electric in the US;  and stereophonic sound systems for motion pictures.

Around the same time, in 1931-2, Bell Laboratories conducted a series of experimental stereophonic recordings with the Philadelphia Orchestra conducted by Leopold Stokowski.  On April 27, 1933, Bell Labs “transmitted” a live performance by the Orchestra at the Academy of Science in Philadelphia to an audience in Constitution Hall in Washington D.C. “that effectively created the illusion of the orchestra’s presence behind the stage curtain.”

These experiments served as the groundwork for the Bell Labs “Symposium on Auditory Perspective” in 1934.  Originally published by the AIEE (now IEEE) in 1934, the full text of these Symposium papers has recently been published on the website of the Audio Engineering Society Historical Committee.  Included are papers by Fletcher, Steinberg, Snow, and Wente, among others, that discuss not only these classic recording and broadcast experiments but the technology that made them — and all subsequent developments in stereophonic sound in the US — possible. If you want to download the Symposium papers, they are available from the AESHC Website as a 4.5 MB pdf file:

The Inventor Of Stereo The Life and Works of Alan Dower BLUMLEIN