The story of a collaboration between Leopold Stokowski of the Philadelphia Orchestra and Harvey Fletcher and others at Bell Labs - part of the decades-long deep dive into sound at Bell Labs.
told by Sheldon Hochheiser - the Bell Labs archivist in the day..
Stokowski was not only one of the world’s foremost conductors; he was a technology enthusiast who firmly believed that technology could contribute to the dissemination and spread of classical music. Stokowski and his orchestra made many acoustic phonograph recordings between 1917 and 1924, and were in 1925 among the first to make an Orthophonic recording through the then-new electrical recording system licensed by the Victor Company from AT&T. He also arranged to have much of the Philadelphia Orchestra’s 1929-1930 season broadcast nationally over the NBC radio network. But he was universally unhappy with the quality of these recordings or broadcasts.
Bell Labs and its predecessor, the Western Electric Engineering Department, had been studying ways to improve the transmission, recording and reproduction of sound since the 1910s as a central part of its mission to perfect the quality of sound for the telephone network. To do so, the researchers wanted to record telephone transmissions. But the phonograph of the day was an acoustic/mechanical device. There was no electricity; and thus no way to directly couple the recording equipment to the telephone. Moreover, the frequency response was limited and uneven.
A team led by Joseph Maxfield solved the problem by inventing a system for electrical recording. AT&T then licensed the new technology to the recording industry. Victor began issuing electrical “Orthophonic” records in 1925. The improvement in sound astonished listeners. Company researchers soon coupled electrical recording to silent movies; the result was The Jazz Singer and Hollywood’s adoption of sound.
Bell Labs continued to work on improving the quality of recorded sound. A team led by AIEE Fellow Halsey Frederick invented new recording techniques, including a moving coil recording arm with a diamond or sapphire recording stylus that tracked a groove vertically (hill and dale) rather than laterally, and with a much smaller force. This provided greater dynamic range and less noise then a conventional recording. Alongside this they devised an improved method of preparing masters from the original wax recording; and gold sputtering, which coated the etched wax with a one-molecule layer of gold, which in turn could be electroplated with copper to produce a surface from which stamping masters for records could be made. Their new system provided a frequency response up to 10,000 Hz (up from 6000Hz) with reduced surface noise and an improved 60 dB dynamic range.
a tip of the hat to Greg