What: On some instruments like a flute or a piano, when the musician sees a note on the sheet music page, like this “C”, the musician plays the instrument, and a “C” note comes out.
That’s not the case for some instruments. On an alto saxophone for instance, when the musician sees the note “C” on the page and plays the alto saxophone with the correct fingerings, an “Eb” note comes out instead of “C”. This occurs because of the saxophone’s length and design. Its fundamental pitch is E-flat and not C. We call these kinds of musical instruments “transposing”. Here are a few more examples:
Some Transposing Instruments:
When a trumpet plays their written C, a Bb note comes out.
When a clarinet plays a C, a Bb comes out.
When a French horn plays a C, an F is produced.
When a baritone saxophone plays a C, an Eb note sounds.
An instrument where the note written differs from the note sounding is called a transposing instrument.
Some Non-Transposing Instruments:
When a flutist plays a written C, a C note comes out.
When an Oboist plays a C, a C comes out.
When a pianist plays a C, a C is produced.
When a violinist plays a C, a C note sounds.
If we read a C, play a C, and the note sounds as a C, the instrument is non-transposing and said to be at concert pitch.
Why: Instruments come in all shapes and sizes, and some instruments sound better when voiced in a different key. Having certain groups of instruments designated as “transposing” makes it easier for a performer to play a whole class of instruments.
For example, the alto saxophone and tenor saxophone play in different fundamental pitches, Eb and Bb. Because they are transposing instruments, the performer only has to learn one set of fingerings or finger shapes. When the saxophonist sees a written note on the staff, she knows that means a particular fingering regardless of which saxophone she is playing. If the saxophones were not transposing, the saxophonist would have to learn a whole new set of fingerings for each of the different saxophones. That’s not very easy! With transposition, the saxophonist can play all the saxophones and can play them all faster with quicker fingerings.
In another example, clarinets come in Bb, Eb, and A. If they were not transposing, the clarinetist would have to remember different fingerings for each of the different clarinets he may be asked to play. Since clarinets are transposing instruments, the performer can get really good at one set of fingerings and play all the clarinets! He knows that a “C” below the staff always means left-hand first three fingers down (with left thumb down on lower key and not on the register key) for any of his clarinets. That becomes muscle memory freeing his brain to focus on other things like the conductor’s directions. Music notation for clarinets represents the fingering, not the concert pitch.
Tubas are non-transposing instruments. Tubas come in C, Bb, Eb, and F. Certain tubas are better than others for different types of music or ranges of pitches. A tuba pitched in C is better at playing the theme song for “Lion King” while a tuba pitched in Bb is better suited for a Sousa march such as “The Thunderer”. If the tuba player wants to be proficient and available on all types of tubas, she will have to learn different fingerings and valve combinations for each of the different tubas. If tubas were transposing, she would only have to learn one set of fingerings and could concentrate on other stuff like dynamics and tricky rhythms. Since that’s not the case, the tubist must spend time in the practice room learning each of the finger/valve combinations for each tuba. Why aren’t tubas transposing? The short answer is tradition, and no instrument that plays in bass clef is transposing.* Music notation for tubas represents the concert pitch, not the finger/valve positions.
When: This often confusing topic arises when the director asks the ensemble to play a “Concert Bb” for tuning purposes. What he means is that he wants all the instruments to produce the same pitch; he wants the same note coming out.
The tubas, baritone horns, trombones, violins, violas, cellos, flutes, bassoons, and oboes will all think Bb, finger their instruments for Bb, and make the Bb pitched sound come out of their instruments.
However, the trumpets, clarinets, and tenor saxophones will all think C, and finger their instruments for the note C so that an actual Bb pitched sound will come out of their instruments. They always have to think “one note up!”
Likewise, the alto saxophones, baritone saxophones, and alto/tenor horns must all think G. They must finger their instruments for the note G so that the requested Bb pitched sound will actually come out of their instruments. They’re usually thinking something like “third note down!”
The French horns will be thinking and playing their note F to produce the desired “Concert Bb” note. “Concert Pitch” from the director means the actual or real note being sounded (not what note the transposing player must think or finger).
A director may ask a particular instrument for “their Bb”. “Clarinets, let me hear your Bb there in measure number ten,” for example. In this case, he wants the clarinet’s Bb. The pitch that will actually come out will be Ab or a “Concert A-flat” note.
In modern, western music, we all agree to use the same names for the same sounds. This system is called Concert Pitch. In concert pitch, note “A” is defined as having a frequency of 440 hertz. All other pitches relate to “A-440” using equal temperament tuning. We’ll sometimes also hear “A-440” referred to as “Low Pitch”.
How: How do we apply this at rehearsal? We learn our scales ahead of time and know which scales must be played on our instruments to match the Concert Pitch requested by the director. It can be tricky sometimes, so be patient with yourself and others when it gets all jumbled up and confusing! Here are some handy charts that can aid in figuring it out:
Who: Who came up with this? Composers invented this idea! By designating certain groups of instruments as transposing, the songwriter does all the hard, pitch conversions ahead of time before the sheet music gets to the performers. This relieves the musicians from having to do the challenging transpositions in their heads while also trying to sight-read. It’s incredibly convenient for the player!
Where: The idea of transposing instruments gets introduced in Beginning Band around the start of book-2. We revisit the concept regularly during Concert Band rehearsal. In time, it will all start to make sense. Remember, the term “transposing instrument” is not actually a description of the instrument itself; the term describes the way we write a particular instrument’s music down on paper by convention.
* Update: Whoops, there's always exceptions to the rule! The Wagner Tuba is indeed a transposing instrument that plays in the bass clef. (It's not really a tuba though. Richard Wagner invented a special type of horn for his operas.) A tenor Wagner Tuba in Bb sounds a major second lower than written, and a bass Wagner Tuba pitched in the key of F plays a whole fifth lower than what's notated on the bass clef staff. Regular horn players will usually double on the Wagner Tuba when required.