Voder

The Bell Telephone Laboratory's Voder was the first attempt to synthesise human speech by breaking it down into its component sounds and then reproducing the sound patterns electronically to create speech.

The Voder actually produced only two basic sounds: a tone generated by a radio valve to produce the vocal sounds and a hissing noise produced by a gas discharge tube to create the sibilants. These basic sounds were passed through a set of filters and an amplifier that mixed and modulated. Eventually what came out sounded like speech. To get the machine to talk required an operator to manipulate a set of keys and a foot pedal to convert the hisses and tones into vowels, consonants, stops, and inflections. In fact the operator needed a year's practice just to master operation of the keys.