All woodwind instruments have a finite set of fingerings. Within a given note range, the fingering for each note will be different. However, when you get to the point where you’re learning to play a second octave, you’ll find that a lot of the notes have the same fingering. So what’s actually going on physically when you change the pitch of the note without changing your fingering?
When you play a note on a musical instrument, it has a particular frequency. However, there are also harmonics present in the sound. To play one of the higher harmonics on the same note, you have to change the speed of the air you’re blowing into the instrument. You can do this either by blowing harder or by changing your embouchure.
When you’re learning to play a woodwind instrument, you start by learning notes within the lowest section of the instrument’s range. Sometimes the very lowest notes might come a bit later, as they can be a bit harder to play, but in general the lower octave will be the starting point. The reason for this is that they’re the easiest notes to play. This is because you’re playing the fundamental frequency. When the fingering of notes start repeating, you’re moving to higher harmonics.
What are harmonics?
The easiest way to think of harmonics is in terms of a vibrating string. If you have a finite length of string that is tight secured at both ends, it will vibrate up and down between the two ends. If you then put your fingers exactly in the middle of the string, holding it tight, and let it vibrate again, it will vibrate up and down between each end and your finger. The length of string that is vibrating as one piece is then halved, but it is still one piece of string of the same length as before.
You can split the string into an infinite number of equal parts. The nth harmonic is the harmonic with n nodes in the string. A node is a stopper on the string, for example, your finger. The frequency of the note is n+1 multiplied by the fundamental frequency. Every frequency has a unique pitch, so by moving to a different harmonic, you are changing the pitch of the note you’re playing.
The easiest harmonic to think about is the one with a single node. The frequency of this note is 2x the fundamental frequency. Doubling the frequency of a note is equivalent to going up by an octave, e.g. from A4 to A3. The higher harmonics then correspond to different intervals, depending on the number of nodes.
How do you play harmonics?
You might not realise it, but you actually most likely play harmonics on your instrument without even knowing. This most commonly happens on the flute. The flute doesn’t have an octave key, unlike the other woodwind instruments, so to play an octave higher you have to overblow. Overblowing is achieved by increasing the speed of the airstream and adjusting your mouth position. It takes some practice but will become natural and a part of your playing.
This means that anything in the second octave up on the flute is a harmonic. You adjust the position of your mouth and the air speed and the note comes out higher. On other instruments this isn’t always the case. Most woodwind instruments have an octave key that opens an additional tone hole, allowing the higher notes to sound more easily. However, even without using the octave key, it will be possible to overblow to higher harmonics on any woodwind instrument.
Depending on the shape of the boar of the instrument you’re playing, the first harmonic that comes out may or may not be the octave above. For example, for the clarinet family of instruments, overblowing a note gives you a note that is an octave and a fifth above the fundamental frequency. This is the harmonic with two nodes. For the other woodwind instruments, the first note you get when you overblow is the octave.
The first harmonic is the easiest to sound on your instrument, and as you go up through the harmonic series, it becomes more and more difficult. This is because you have to increase the speed of the air stream more and more to get higher and higher frequencies. This is also why high notes are generally more difficult to play on most instruments.
How can I learn to play harmonics?
The best way to learn to play harmonics is just to keep practice overblowing. On the flute, this can be a bit more tricky, because you don’t have an octave key to help you out. However, the first harmonic is generally easier to sound on the flute than on the other woodwind instruments, so this isn’t necessarily an issue.
For woodwind instruments with an octave key, if you can’t initially overblow up to the first harmonic, you can try sounding the note using the octave key, then removing your finger from the octave key but continuing to blow air through the instrument. Hopefully, you’ll remain on the higher pitch. Then try to remember your mouth position while the note is sounding and repeat it but without the octave key. Keep trying this until you get the mouth position without thinking.
The more harmonics you can play, the more you’ll notice an improvement in the quality of your overall sound. This comes from learning to control your mouth position and the air flow into the instrument. You’ll notice that the sound of the harmonics will always be a bit fuzzy, but you’ll most likely get a clearer sound when you play the same notes with the correct fingering.
Summary
To sum up this post, the reason you can play multiple notes with the same fingering is that there are harmonics present in the fundamental frequency that you can access via overblowing. This is the case for all woodwind instruments, although when you overblow on an instrument in the clarinet family, you miss the first harmonic, due to the shape of the bore of the instrument. Learning to play harmonics can improve your overall sound quality on your instrument, so they’re always worth practicing.