The Trumpet as a Transposing Instrument
There are three basic tunings for musical instruments, these being "concert" or C instruments (e.g., piano, guitar, flute or violin), B flat instruments (e.g., tenor sax, clarinet or trumpet) and E flat instruments (e.g. alto or baritone sax). What this means in practical terms is that if you play the same written note on each of these three types of instruments, a different note will sound for each of the three types.
The reason for the different tunings is the actual length of the tubing required to make the instruments themselves, along with ease of playing. The Bb and Eb instruments are referred to as transposing instruments. If you play a C note on a Bb instrument, the sound that actually comes out is a concert Bb note.
If you play a C note on an Eb instrument, the sound that actually comes out is a concert Eb note. Once you have a good knowledge of intervals, it is easy to understand the relationship between the three tunings. If you see a note written for a concert instrument (e.g., C) you would have to play a note one tone higher on a Bb instrument to get a concert C note to sound (play a D note).
To sound a concert C note on an Eb instrument, you would need to play a note a major sixth higher (an A note). This is a general transposing principle with these instruments whenever you are playing with other musicians or are reading a part written for a concert instrument. The chart below shows all concert pitch notes in the left column and the equivalent notes for Bb instruments in the center column and Eb instruments in the right column.
