IN THE spring of 1933, Dr. Frank B. Jewett, President of the Bell Telephone Laboratories, presented to the National Academy of Sciences in Washington a technical report and a demonstration of the stereophonic reproduction of music, which included transmission over telephone wires from Philadelphia. Microphones in the Academy of Music picked up the music of the Philadelphia Orchestra; three specially conditioned circuits transmitted it to Constitution Hall in Washington; and there, for a distinguished audience, after suitable amplification it was projected from three loud speakers. In Washington, Dr. Leopold Stokowski, at that time director of the Orchestra, sat at a control box by means of which he could adjust the volume of each loud speaker, and addition modify the tonal quality by augmenting or reducing the amounts of sound at the upper and lower ends of the scale. As part of the demonstration a number of experiments were performed by Dr. Harvey Fletcher of the Bell Telephone Laboratories, who had charge of the development work. On the stage in Philadelphia, a carpenter hammered and sawed, while conversing with his helper; a soloist sang as she walked across the stage; and finally a trumpeter in Philadelphia played antiphonally with another trumpeter on the opposite side of the stage in Washington. It was only when the curtain which hid the loud speakers was raised that the audience in Washington could believe that what they had heard had not happened on the stage before them.
So successful was this production that when a few years later Dr. Stokowski was asked to direct a local orchestra in the Hollywood Bowl, he insisted that a stereophonic system be installed to reenforce the music. The Laboratories had pioneered in the development of sound reenforcement systems and, with the assistance of Electrical Research Products, Inc., undertook this project as a further research in that art. Again the results were successful; some 25,000 people in the open air were able to hear with ease a program of vocal and instrumental music.