A student of Johann Gottlob Krüger (No. 1987.2), Kratzenstein was apparently the first to publish a treatise on electrotherapy, although he may have been publishing experiments devised by Krüger. Second edition, Halle, C.H. Hemmerde,1745. English translation in E. Snorrason, C.G. Kratzenstein and his studies on electricity during the eighteenth century, Odense, 1974.

In the first part of this work Kratzenstein described how the vowels could be produced in the vocal tract. In the  second part he described the construction of a new kind of organ with pipes for each of the vowels. Each pipe had a characteristic resonant cavity which should emulate the vocal tract for the corresponding vowel. In order to excite these resonators he made use of free reeds which at that time were little known. Kratzenstein demonstrated this instrument in Saint Petersburg in 1780; it was damaged and disappeared shortly afterwards. Digital facsimile from digitale-sammlungen.de at this link.