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Für etwaige weitere Interessenten hier die englische Zusammenfassung:

Christian Gottlieb Kratzenstein: inventor
of the organ stops with free reeds -
Christian Ahrens and Jonas Braasch
As a result of the Orgelbewegung in the
early 20th century, frec reeds lost their good
reputation. Nowadays they are built and
respected again.
Christian Gottlieb Kratzenstein (1723-1795)
was the first to use the free reed. He did so
in his ‘speech machine’, which was capable
of imitating vowels. The machine was built
as a tool for scholarly research.
lt is generally believed that Kratzenstein
based his free reed on the ones in the East-
Asian mouth organ. the ‘Sheng’; and that
his reeds had no tuning device, prohibiting
their use in organs. Neither of these ideas is
correct, as can be concluded from the text
that Kratzenstcin sent to the Academy of
Sciences in St. Petersburg in 1780.
Up to now, it is uncertain whether
Kratzenstein developed the new reeds
alone. It is possible that the organ builder
Franz Kirschnick and his pupil Georg
Christoffer Rackwitz assisted him.
Historical sources point out that
Kirschnick was one ofthe first to build free
reeds.
Conclusion: 1781 is the birth year of organ
stops with free reeds.