Sometimes described as the heavy artillery of the orchestra, the brass section is relied upon for bright flourishes, powerful fanfares, and notes of joy throughout a piece, whether subdued or flamboyant.
As well as that it provides a natural counterpoint throughout to woodwind and keyboard led melodies, making it a kind of secondary voice in the performance, harmonising with or reacting to whatever is leading the melody, adding to the texture of the piece and enriching and enhancing the sound.
Favourite brass instruments for the orchestra include the French horn, the trumpet, the trombone, and the tuba. From time to time you may see use of tenor horns, flugelhorns, and cornets, though these are all more rarely used.
A trumpet is noted among brass instruments for its flexibility; it can stay mellow, soft, and perform almost in the same role as the oboe in the woodwind section – but it can also be brought out at the right time in a fanfare or to add to a triumphant crescendo and change the mood. You can expect that over the course of the piece a trumpet will play many roles, and trumpet solos, though rare, are not unknown.
By contrast, the trombone – and in orchestral use, mostly the large, double-tubing bass trombone – is more focused in use and style, providing a deep bass background to most pieces, with the option to add smooth support as the music lifts and the scales shift ever upward. There’s a reason that the trombone is also an essential feature in any swing band; when pushed, it can do some quite startling things.
The ability of the French horn to sustain long, steady notes makes it astonishingly useful to the orchestra and to the composer. These sustained notes are often used to tie the disparate parts of a piece of music together, providing the connection that unifies the performance and holds it together.
The role of the tuba is different again; few instruments can carry the kind of warmth and rich sound of the tuba, and it is second to none in playing melodies along the bassline, giving the piece being played an additional layer of texture which can enliven and enrich the performance as a whole.
The smoothness, richness, and power available to players of brass instruments makes them perfect to play supporting roles throughout a piece while also being able to take on spotlight roles where called upon.
They’re a great complement to woodwind and strings, the contrast between them crisp, clear, and always an extra layer of nuance available to the music, but unlike the percussion section they can take and sustain a lead role for some time where necessary, or provide a powerful fanfare where appropriate.