How do I play a Brass Instrument?

There's a bit of science and a bit of skill involved. It helps, in my opinion, to understand the science, because it makes it easier in the long run! The second page in this introduction has a brass instrument fingering chart.

The science

A Brass Instrument is effectively a long pipe. Within a pipe of a particular diameter and length, it's possible to set up a 'standing wave' and get the pipe to resonate.

The picture above shows one complete wave in the pipe. The distance between a pair of corresponding peaks is called the wavelength. The wavelength depends on the speed and the frequency. Since the speed of sound in air is essentially fixed, all we can do is vary the wavelength or the frequency. If we make the pipe longer or shorter, we can alter the wavelength which affects the frequency.

The other trick is that we know that we can make a pipe resonate at a higher frequency than it's fundamental frequency by getting more than one standing wave in the pipe.

These additional resonant frequencies are called harmonics. You can only have a harmonic where you can get a complete wave in the pipe. You can't have a bit of wave hanging over the edge. So, stimulating the pipe to vibrate at a higher frequency means we can get extra notes out of it. That's part of the skill!

Valves

What we've just done is invent a bugle. It's a pipe that we get to vibrate at different resonant frequencies by buzzing our lips at the appropriate frequency to set up a standing wave in the pipe. Because of the science, we can only get a limited number of notes corresponding to the differenct harmonics.

But, if we could alter the pipe length, that gives us a whole range of possibilities, because evry pipe length will generate a different family of notes.

So, brass instruments have valves, and all they do is change the length of the tubing.

The tubing lengths are carefully calculated to make the pipe just the right length (give or take a bit) to get the notes we want.

One valve increases the main tube length by enough to lower the frequency by a semitone. One valve lowers the frequency by a tone (two semitones) and the third lowers the tone by 3 semitones. For some reason unknown to me, these are, in order, the 2nd, 1st and 3rd valves.

That's the (albeit very basic) science. Exit here for fingering charts!

Alternatively, read on for the advanced learners science class!

Advanced Science

There are a couple of simple bits of maths underpinning music.

Firstly, the equation that relates frequency and wavelength:

speed of sound = frequency * wavelength

The speed of sound in dry air is around 330m/s (metres per second for you Americans).

Imagine I've got a trumpet which uncoiled is around 54" which is 1.371 metres. Doing a bit of simple algebra, we can rearrange the above equation to get:

frequency = speed of sound / wavelength

...and plugging in some numbers...

frequency = 330 / 1.371 = 241Hz (Hz = hertz = unit of measure of frequency)

So, our fundamental note for a trumpet with no valves down is one with a pitch of 240Hz.

Here's an interesting reference article on brass instruments. This article explains how the mathematical relationships work. I've used both these as reference material in the above description. Also, here's a reference chart of notes to frequencies.