In the 20.06.27 MMD Lee Rothrock writes about a clock in the film
"They Came By Night."  That clock is a typical Black Forest Trumpet
item.  It appears to be from around 1880.

https://youtu.be/Mtklzx3QD44?t=2750
 

Robbie Rhodes is correct: the sound is made from a reed to which
is attached a tin plate conical tube to try to make it sound
trumpet-like.  There may be anywhere from three to fourteen of them.

The music or fanfare is done with a pinned wooden wheel, the pins
of which operate stickers, opening a valve and allowing the reed
to sound.

I have restored around a dozen of these and am working on an
eight-trumpet version at the moment.  The most prolific maker was
Emilian Wehrle of Furtwangen, but there were one or two others.

John Harrold