Open Access

Fabian Brackhane

• One was a distinguished natural scientist and engineer, the other a self-taught scientist and vilified as a conman: Christian Gottlieb Kratzenstein (1723–1795) and Wolfgang von Kempelen (1734–1804). Some of the former’s postula-tions on human physiology and articulation of speech proved wrong in later years. Most of the latter’s theories are considered applicable even today. The perhaps most contrasting approaches to speech synthesis during the 18th century are linked to their names. There are many essential differences between their approaches which show that these two researchers were not only representatives of different schools of thought, but also representatives of two different scientific eras. A speculative and philosophical approach on the one hand versus an empirical and logical approach on the other hand. Both Kratzenstein and Kempelen published books on their research. But while the “Tentamen” [4] of the physician Kratzen-stein remains rather vague and imprecise in its descriptions of vowel production and synthesis, the “Mechanismus” [8] of the engineer Kempelen shows much more precision and correctness in almost every respect of human speech and lan-guage. The goal of this paper is to discuss the differences between these two con-temporaneous researchers on speech synthesis and to compare their theories with present-days findings.