Hochschule für Musik Detmold
Abstract :
The bell of a trumpet is a flaring horn which has two functions: on the
one hand, it terminates the resonating bore and therefore controls
the sound reflections traveling back to the mouthpiece. On the other
hand, the bell controls the impedance match between the narrow
downstream bore and the surrounding air in a room, and the
radiation directivity.
The cylindrical bore downstream of the mouthpiece can favor non-
linear wave steepening: The “brassiness” of the sound perceived in
the room depends on the amplitude of the pressure peaks inside the
mouthpiece.
To investigate these phenomena sound pressure measurements have
been performed on a trumpet, with sensors inside the mouthpiece,
and at different distances from the bell using “musical” excitation
signals (generated by a trumpeter) and pulselike technical excitation
signals, at various levels.