Editing Mechanical synthesis (section)

== Christian Kratzenstein: Generating vowels with acoustic resonators ==
[[wikipedia:Christian_Gottlieb_Kratzenstein|Christian Gottlieb Kratzenstein]] is known in phonetics for being one of the earliest scientists to openly share his endeavours in speech synthesis. His achievement to approximate the synthesis of the vowels /a, e, i, o, u/ through resonating pipes is notable, given the fact that the understanding of acoustic resonance was still a work in progress. Through a process of trial and error<ref name=":2">Ohala, J. (2011). Christian Gottlieb Kratzenstein: Pioneer in Speech Synthesis. ''ICPhS2011 XVII''.</ref>, Kratzenstein's work reveals that the complexities of speech can be explained in physical and physiological terms, while highlighting that the principles behind speech synthesis are somewhat similar to those governing musical instruments.

Born in 1723 in Wemingerode, Germany, Kratzenstein studied natural sciences at the University of Halle, where he obtained his doctorate in 1746. He then became a professor of mechanics at the St. Petersburg University (1748-1753) and later at the University of Copenhagen (from 1753 until his death in 1795).

In 1779, Leonhard Euler proposes a competition at the Academy of Sciences in St. Petersburg, asking whether it might be possible to construct a set of pipes which would perfectly immitate the vowels /a, e, i, o, u/ <ref name=":3">Story, B. (2019). Chapter 1. History of Speech Synthesis. In ''Routledge Handbook of Phonetics'' (pp. 9–32). Routledge.</ref>. Kratzenstein submits the work he had been gathering on this topic for over five years<ref name=":2" /> and wins the competition by describing the nature of the differences between the five vowels in question, as well as implementing their 'synthesis' (rather: approximation) through resonating pipes. Building on prior information known at the time about speech production, Kratzenstein provides precise measurements of the jaw movements and lip openings as cues for differentiating the acoustic features of vowels; then he proceeds to build five flute-like acoustic resonators made of wood and metal, which he likely shaped through trial and error to create approximations of the five vowel sounds when blown with a free reed. A detailed account of this approach to mechanical speech synthesis was first published in Latin, shortly followed by a French translation<ref name=":2" />.