Homer Dudley's 'Voder' of 1939.
"Parallel Bandpass Vocoder" (1939) Homer.W. Dudley: speech analysis and resynthesis.
"The Voder speech synthesizer"(1940) Homer.W. Dudley: a voice model played by a human operator.
The Vocoder (Voice Operated reCorDER) developed by Homer Dudley,
a research physicist at Bell Laboratories, New Jersey USA, was
a composite device consisting of an analyser and an artificial
voice. The analyser detected energy levels of succesive sound
samples measured over the entire audio frequency spectrum via
a series of narrow band filters. The results of which could be
viewed graphically as functions of frequency against time.
The synthesiser reversed the process by scanning the data from
the analyser and supplying the results to a feedback network of
analytical filters energised by a noise generator to produce audible
sounds.
A sound sample from Dudley's 1939 Voder, with introduction (170k au file)
The fidelity of the machine was limited, the machine was intended
as a research machine for compression schemes to transmit voice
over copper phone lines. Werner Meyer-Eppler, then the director
of Phonetics at Bonn University, recognised the relevance of the
machines to electronic music after Dudley visited the University
in 1948, and used the vocoder as a basis for his future writings
which in turn became the inspiration for the German "Electronische
Musik" movement.
"At the 1939 World's Fair a machine called a Voder was shown .
A girl stroked its keys and it emitted recognsable speech. No
human vocal cords entered into the procedure at any point; the
keys simply combined some electronically produced vibrations and
passed these on to a loud-speaker."
("As We May Think" by Vannevar Bush, 1945. )
