+++ INTERSPEECH 2015 – February Update ++

A View from Dresden onto the History of Speech Communication

Part 2: Von Kempelen's 'Sprachmaschine' and the beginning of speech synthesis

Complete article including figures available at: http://interspeech2015.org/conference/historical-review/

The speaking machine of Wolfgang von Kempelen (1734-1804) can be considered as the first successful attempt of a mechanical speech synthesiser. The Austrian-Hungarian engineer is still famous for his 'chess turk' but it was his 'Sprachmaschine' that can count as a milestone in (speech) technology. In his book 'Mechanismus der menschlichen Sprache nebst der Beschreibung einer sprechenden Maschine' (published 1791, no English translation yet) he described the function of the machine which was intended to give a voice for deaf people. Contemporary personalities like Goethe confirmed the authenticity of a child voice when the speaking machine was played.

How does the machine work?

The machine consists of bellows that is connected with a tube to a wooden wind chest. On the other side of the wind chest a round wooden block represents the interface to an open rubber funnel (as the vocal tract). In the wind chest there are two modified recorders to produce the fricatives [s] and [S]. The voice generator is located inside the wooden block. The artificial voice is generated with the help of a reed pipe borrowed by the pipe organ. It has an ivory reed vibrating against a wooden hollow shallot (like in a clarinet). The trained human operator plays the machine like a musical instrument. The right elbows control the air pressure by pressing on the bellows, two fingers of the right hand close or open the access for stops and nasals, two other fingers of the right hand for the fricatives. Vowels are performed by the palm of left hand in different ways.

Replicas

Apart from parts of one of the originals that are hosted at the Deutsches Museum in Munich there are several reconstructions based on Kempelen's quite detailed descriptions. The replicas built in Budapest, Vienna, York and Saarbrücken allow a lively demonstration of the mechanical generation of speech as well its acoustic analysis but also perception tests with today's listeners. Interestingly, the art of constructing artificial voices led to the profession of 'voice makers' in Eastern-German Thuringia (more information in one of the next newsletters). Original products of the Thuringian 'Stimmenmacher' as well as one of the replicas located at TU Dresden are at display of the HAPS (Historische Akustisch-Phonetische Sammlung) available for ears, eyes (and hands) at the re-opening of HAPS at 4 Sept, which is also the start of the Interspeech satellite Workshop on The History of Speech Communication Research (HSCR 2015).

Jürgen Trouvain and Fabian Brackhane