AT&T Tech Channel

About this video

This film takes the viewer behind the scenes at Bell Laboratories while the new motion picture sound systems were being invented and tested. The foray into motion picture sound was a natural move for the Bell System -- already specializing in communications - but it also had a high profile at the time. This film, made using the Vitaphone sound developed at the Labs, shows testing of huge theater speakers, a visual light method of microphotography, the cutting of a wax disc for a Vitaphone system, and fatigue tests for equipment and film.

The most interesting part of the film is the display of the then-experimental soundtrack method of film sound: a thin tape was applied to the side of filmstrip - the sound track - and it vibrated with voices from a microphone. As the film states, "the voice photographs itself". Then Francis F. Lucas, a leader in microscopic photography, examines the film and soundtrack under UV light.

Due to a support agreement with Warner Brothers, soon the Bell System's methods of sound recording and playback were prevalent in Warner theaters nationwide - over 1,000 by the end of 1928.

Footage courtesy of AT&T Archives and History Center, Warren, NJ

Release date: 06/20/2011