We hear sound when vibrations in air reach our ears.
Find out how here on our What is Sound? page where you will read how plucking a string on a ukelele (or guitar or violin etc) makes it vibrate, and this causes the air around it to vibrate. A sound wave of vibrating air then travels across the room – like ripples across a pond after a stone is dropped into it. The sound wave reaches our ear and we hear sound.
BUT … cornets and trombones don’t have strings! So how do we make sound with a brass instrument?
To make sound in a brass instrument we need to make the air inside it vibrate and we do this with our lips by buzzing!
Buzzing is done by pulling the corners of the mouth into the cheeks and blowing fast through the centre of the lips.
We are working on making our own tutorial on buzzing but in the meantime you can find some good videos on YouTube like this one: video on how to buzz.
The sound we hear depends on how fast or slowly the air vibrates. Fast vibrations produce a high sound and slow vibrations produce a low sound. We call this the “pitch” of the sound.
In a brass instrument, if we vibrate our lips fast we produce a high-pitched sound, and if we vibrate our lips slowly we produce a low-pitched sound.
The notes we can play also depend on the length of the tubing of the instrument. If the tubing is longer then the note is lower. If the tubing is shorter the note is higher.
Large instruments like tubas produce lower sounds than small instruments like cornets and trumpets because they have longer tubing. For example, a B♭ Tuba has twice the length of tubing of a trombone or baritone horn, and they have twice the length of tubing of a B♭ Cornet.
We can make the tubing longer on a trombone by pushing the slide out and shorter by pulling the slide back in.
On a valved instrument such as a cornet or trumpet we can make the tubing longer by pressing valves and opening up the additional lengths of tubing attached to the valves.
Read more about how valves are used to change the note played.
But we can also produce different notes from a trombone without moving the slide, or from a valved instrument without pressing any valves. Only certain notes can be produced like this and they are related to each other as harmonics. Read about harmonics here.
Note that we don’t play a brass musical instrument by singing or humming into it, although some experimental music does include some of that!
Nor do we play a brass musical instrument by whistling. When we whistle, we blow air through our lips in a way that makes the air vibrate without our lips vibrating, which is different to buzzing. To find out more visit how to whistle on wikihow.
See also our pages about music in general
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