How was the operation of the Voder, developed by Homer Dudley, primarily controlled when unveiled at the 1939 New York World's Fair?

Answer

Manually by a human operator using a keyboard and foot pedals.

The Voder (Voice Operation Decoder) represented a significant step in electromechanical speech synthesis but was not an automated text-to-speech (TTS) system in the modern sense. Instead, it functioned as an articulation synthesizer requiring direct, real-time manipulation. A human operator controlled the device using a physical keyboard and separate foot pedals. By manipulating these controls, the operator could adjust the sound source and the vocal tract filters within the machine, effectively mimicking the human process of phonation and articulation to produce spoken words. This dependency on constant human skill and intervention contrasts sharply with later automated systems that relied on input like text or electronic signals.

How was the operation of the Voder, developed by Homer Dudley, primarily controlled when unveiled at the 1939 New York World's Fair?
inventiontechnologyvoicesynthesizerspeech synthesis