Media and Prosthesis: The Vocoder, the Artificial Larynx, and the History of Signal Processing

Vocal Codes

American Telephone and Telegraph (AT&T) commemorated the twenty-fifth anniversary of the first transcontinental telephone conversation with another telephonic event. On July 29, 1939, a tribute call was placed between the bicoastal World’s Fair sites. Not much was said—the transcript records these ordinary lines:

“Hello, San Francisco. Hello, everybody, this is New York speaking. Greetings to you in San Francisco.”

“Hello, New York. This is San Francisco. Greetings and best wishes to New York.”²

Fig. 1.

Voder room, Golden Gate Exposition, San Francisco, 1939. Courtesy of AT&T Archives and History Center.

Fig. 2.

Voder float at Golden Gate Expo. Courtesy of AT&T Archives and History Center.

What made this exchange extraordinary was that it took place between two talking machines—two Voders, or Voice Operation DEmonstratoRs. Bell engineers nicknamed these machines “Pedro” after the emperor of Brazil, who tested the telephone at the 1876 Philadelphia Centennial (“My God, it talks!”). The emperor became the emblem of naive astonishment in subsequent publications, which reminded readers, “The telephone didn’t talk, it carried talk.”³ But with “Pedro the Voder,” AT&T announced the arrival of the World of Tomorrow.

Advertised as the first technology to create true speech without recourse to film or phonographic recording, the Voder went beyond previous automata in its ability to turn out full sentences composed from any combination of sounds.⁴ It furthermore produced assorted inhuman sounds, from a pig’s squeal to a voice of impossible bass, all with an “electrical accent.” Five million visitors attended the exhibit in New York alone; many had difficulty comprehending the new medium of speech synthesis. (“Is it true that there really is no phonograph record? . . . It’s amazing!”⁵)

The Voder was outwardly similar to a parlor organ. The white keys produced vowels; the black keys acted as “stop” consonants (such as t and d), cutting off airflow; and a foot pedal changed the pitch. In New York, AT&T vice president J. O. Perrine demonstrated the machine with the help of a “Voderette,” one of twenty-four telephone operators who trained a full year for the World’s Fair event. Their performances included slides that analogized the Voder’s components to parts of the human vocal tract. Perrine told audiences that this technology might “enable mutes to talk.” “Some day,” he predicted, “it may be possible for a telephone circuit to have a narrow frequency band in order to transmit only the specifications for the voice. Then, we will talk into a transmitter, just as we do now, but the line will carry a signal to a device at the other end of the circuit which will recreate our words for the listener there.”⁶

One of the Voder’s most prominent spectators was Vannevar Bush, director of the federal Office of Scientific Research and Development. In the 1945 article “As We May Think,” Bush proposed the Voder as one element of his Memex, a memory-extending desk or information-management system, which famously influenced Theodore Nelson’s theory of hypertext. Bush saw in the Voder a technique for orally making, consulting, and compressing records, one that might supersede the time-consuming and “artificial” actions of writing and typing. Moreover these records could be automatically transmitted as electrical signals, interconverted between the senses, and displayed by multimedia machines:

To make the record, we now push a pencil or tap a typewriter. Then comes the process of digestion and correction, followed by an intricate process of typesetting, printing and distribution. . . . Will the author of the future cease writing by hand or typewriter and talk directly to the record? . . . At a recent World Fair a machine called a Voder was shown. A girl stroked its keys and it emitted recognizable speech. No human vocal chords entered into the procedure at any point; the keys simply combined some electrically produced vibrations and passed these on to a loudspeaker. In the Bell...