Voder

The Bell Telephone Laboratory's Voder (abbreviation of Voice Operating Demonstrator) was the first attempt to electronically synthesize human speech by breaking it down into its acoustic components.

A buzz tone generated by a relaxation oscillator produced the voiced vowels and nasal sounds, with the pitch controlled by a foot pedal.

These initial sounds were passed through a bank of 10 band-pass filters that were selected by keys; their outputs were combined, amplified and fed to a loudspeaker.

The filters were controlled by a set of keys and a foot pedal to convert the hisses and tones into vowels, consonants, and inflections.

In 1948, Werner Meyer-Eppler[5] recognized the capability of the Voder machine to generate electronic music, as described in Dudley's patent.

Schematic circuit of the VODER [ 1 ]
Voder demonstration by Bell Labs at the 1939 New York World's Fair [ 3 ]