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Von Kempelen's talking machine, 1791

In 1791 Wolfgang von Kempelen
"constructed and demonstrated a more elaborate machine for generating connected utterances. [Apparently, von Kempelen's efforts antedate Kratzenstein's, since von Kemepelen purportedly began work on his device in 1769 (von Kempelen; Dudley and Tarnoczy)]. Although his machine received considerable publicity, it was not taken as seriously as it should have been. Von Kempelen had earlier perpetrated a deception in the form of a mechanical chess-playing machine. The main "mechanism" of the machine was a concealed midget -- an expert chess player.

The speaking machine, however, was a completely legitimate device. It used a bellows to supply air to a reed which, in turn, excited a single, hand-varied resonator for producing voiced sounds. Consonants, including nasals, were simulated by four separate constricted passages, controlled by the fingers of the other hand. An improved version of the machine was built from von Kempelen's description by Sir Charles Wheatstone (of the Wheatstone Bridge, and who is credited in Britain with the invention of the telegraph). It is shown below."

James L. Flanagan, "Speech Analysis, Synthesis and Perception", Springer-Verlag, 1965, pp. 166-167.

Wheatstone's construction of von Kempelen's speaking machine

"Von Kempelen had not been challenged with the replication of vowel sounds and, therefore, had aimed at a more complex traget of creating phrases and multiple word sounds. As with Kratzenstein's device, his system employed a bellows to supply air for a vibrating reed which served as the vocal cords. The resonators of the mouth were simulated by a flexible cylindrical leather tube which, through hand manipulation, could produced voiced sounds. The strange mechanical device also had openings to simulate the nasal resonators and two lever-operated whistle tubes to create the fricative sounds from the teeth and lips. The device was quite ingenious but required a considerable amount of skill and experience of the operator. As he "played" the device, he had to perform simultaneous actions not unlike those required to play the large musical organs of those times. Surprisingly enough, the talking machine had considerable human engineering built in so that a single operator could produce truly synthetic speech. As he sat beside the speaking machine with his right arm resting on the bellows, he controlled the nostril openings, the reed bypass pluynger, and the whistle levers with his right hand. His left hand was free to manipulate the leather speech tube to articulate the voiced sounds from the vibrating reed. According to von Kempelen, his machine produced 19 consonant sounds which could be understood. Whether those sounds could be equally well understood by people other than von Kempelen might be questioned because of ... operator bias ...

Although the "speaking bellows" conceived by von Kempelen was ultimately refined and constructed by Sir Charles Wheatstone, very little research in similar directions followed until the turn of the 19th century."

John P. Cater, "Electronically Speaking: Computer Speech Generation", Howard M. Sams & Co., 1983, pp. 72-74.