Page 14 - Summer2019

Early Talking Automata
vibrating under tension and blown by the glottal air flow to
_~ . create sound, and a tube shaped like the vocal tract to form
"’ l‘ sound into speech.
1 fr; .1;
Mechanical analogs were proposed, drawing again on com-
xt " parisons with musical instruments: a pair of bellows for
i . the lungs, a vibrating reed or membrane for the vocal folds,
' and organ pipes for the mouth and nose. Only the control
. mechanism and the confidence that a mechanical speaking
\' machine could actually be built were lacking. These were
3 >2 . V provided by Vaucanson (1738), who constructed an automa-
‘ ‘ ‘ it ton flute player that played tunes by blowing into a real flute.
"-. Drawing on a long history of mechanisms used in musical
\ clocks and chamber organs (cf Kircher, 1650), dating back
to before the middle ages, Vaucanson ingeniously employed a
revolving cylinder studded with pins to coordinate the timing
and activation of a set of levers moving the articulators of
Figure 1. Midsagittal section of the vocal tract from the first color his automaton, leaving physics to do the rest. Generalizing
anatomy lrook of the head and neck. All of the structures of the the sa.me idea, Engramelle (1775) later published a mono-
respiratory, oral, and nasal tracts are accurately lalreled in exquisite graph detailing how individual musical performances could
detail, including the trachea (x), vocal folds (85), jaw (p), tongue be systematically transcribed onto pinned cylinders, as in a
(65), palate (54), velum (45), and lips (L, M). The flow of air from the modern music box, and used to drive a mechanical organ
trachea through the vocal folds into the oral and nasal cavities was for playback. These were the first examples of programmable
clearly understood as was the Vilrration of the Vocal folds; the shaping musical instruments and also the first examples of musical
of the oral cavity by the jaw, tongue, and lips; and the action of the automata designed to reproduce the actions of human musi-
velum in closing of the nasal cavity during speech. Reproduced from cians. It did not escape the imagination of contemporaries of
Gautier d'Agoty and Duverney (1745). both Vaucanson and Engramelle that the same mechanism
could also be used to synthesize human speech (Doyon and
Liaigre, 1966; Séris, 1995).
these apparently contradictory viewpoints, Ferrein himsel.f,
and later Vicq d'Azyr (1779), concluded that the vibration Kratzenstein's Vowel Tubes and Kempelen's
of the vocal folds, the shape of the glottis, and the glottal Speaking Machine
airflow could not be meaningfully separated and were all The firstinstantiation of Mersenne's original proposal appearedin
responsible for sound generation, in many respects predict- 1780, whm Christian Gottlieb Kratzenstein, a professorin Copen-
ing the modern myoelastic-aerodyna.mic theory of vocal hagen, won first prize for a competition proposed by Leonha.rd
fold vibration (van den Berg, 1958). By the middle of the Euler at the Imperial Academy of St. Petersburg in 1777. Euler
eighteenth century, the analogy between the vocal tract and asked whether it might be possible to construct a set of organ
a very special kind of musical instrument was no longer in pipes similar to the traditional vox humana stops, which would
doubt. The open issue was how to “play” the vocal instrument perfectly imitate the vowels a, e, i, 0, and u. Kratzenstein (1780)
to produce speech. responded by making five tubes of metal and wood (Figure 2)
that he shaped by trial and error to produce approximations of
Mechanical Reproduction of the Voice the diffaentvowel soundswhen blown withafree reed. Notably,
It took until the late eighteenth century for all of these early none of these bore any recognizable resemblance to the shape of
ideas by Mersenne, Dodart, and Ferrein to be fully explored an actual vocal tract.
and implemented. The basic component mechanisms under-
lying speech production were by now understood: a pair of At around the same time, Wolfgang von Kempelen spent 20
lungs to create an aerodynamic flow, a pair of vocal folds years several attempts to create a mechanical speaking
12 | Anal.-u.a1-t.:igy| Summer 2019