The trumpet has 3 valves that alter the pitch within a harmonic series of the instrument. This is due to each valve having a different length of tubing.
Post by StephenR
The trombone is the only brass instrument that doesn’t use valves to change the pitch within a harmonic series of notes.
Music Exams are one of the scariest things in music. All that work leading up to that one performance with an examiner watching you......Wrong!