Schalmei - Signal Horns
The Schalmei is a signal horn. It is actually a reed instrument that produces a very loud sound. It is very much like a rubber bulbed horn. When no valves are pressed the air goes through a reed and bell(s). When a valve is pressed, the air goes through a different reed and bell(s) which produce a different sound.
These have been widely used in Germany as a signal horn for over 100 years. They were used by train conductors to send signals. They were also used during WWII by Nazi youth in parade bands. If you have more information on Schalmei horns, please send it to me.