How an Orchestra Is Organized

A symphony orchestra can look like a sea of musicians, but its organization is quite logical. The instruments are grouped by family and placed on stage according to the volume, tone color, and function of each. With the structure in mind, it becomes much easier to follow what happens during a concert.

The four sections

The modern symphony orchestra divides into four main sections: strings, woodwinds, brass, and percussion. Each has its own sonic profile and plays a specific part in building the music. For the logic of this division in general, it is worth reading about the main families of musical instruments.

The strings form the core of the orchestra, both in numbers and in sonic presence. They include violins (divided into firsts and seconds), violas, cellos, and double basses. The woodwinds include flutes, oboes, clarinets, and bassoons, along with their relatives such as the piccolo, English horn, bass clarinet, and contrabassoon. The brass bring together French horns, trumpets, trombones, and tuba. The percussion covers timpani, drums, cymbals, triangle, xylophones, and many others.

How the musicians are seated

The arrangement varies with the era, the conductor, and the hall, but there is a widely used classic layout. The strings sit in front, in a semicircle around the conductor: violins to the conductor's left, cellos and violas in the center or to the right, and the double basses at the back, usually on the right. Behind them sit the woodwinds, in two rows. Farther back come the brass and, at the farthest point, the percussion, including the timpani.

The logic is acoustic. Louder instruments, such as brass and percussion, sit farther from the audience and the conductor so that they do not drown out the softer ones. The strings, with their more delicate sound, sit near the audience. There is also a concern to place instruments that converse with each other, such as woodwinds and strings, where the players can hear one another. In the antiphonal seating common to many orchestras, the second violins sit on the right, facing the firsts, which separates the two lines.

The role of each section

The strings usually carry most of the orchestral texture, since their sustained and flexible sound suits both melody and accompaniment. The violins take the highest line and often the main theme, the violas fill in the inner harmony, the cellos sing melodies in the middle register or reinforce the bass, and the double basses provide the foundation. The acoustics of the section are explained in how bowed string instruments work.

The woodwinds bring color. Each instrument has an individual tone: the flute is airy, the oboe nasal and penetrating, the clarinet round and dark, the bassoon full-bodied and woody. The brass give brilliance, power, and solemnity, and the percussion marks rhythm, highlights accents, and creates color effects. The difference between woodwinds and brass, including instruments that defy the logic of their names, is explained in the article on woodwind versus brass instruments.

Hierarchy within the section

Each string section is led by a principal, also called a section leader. The principal of the first violins is the concertmaster, who serves as the orchestra's first violin and as the link between the players and the conductor. The concertmaster leads the tuning process and decides, together with the section, the bowings, meaning the direction of the bow in each passage, so that everyone plays uniformly.

Among the winds, the principals share the material with assistants and, in some works, with soloists. The timpani have a principal timpanist. The hierarchy lets technical decisions flow without depending on the conductor for every detail, and it organizes the internal listening of the group.

The conductor and the tuning

The conductor is the leader of the ensemble and looks after tempo, dynamics, balance among the sections, and interpretation. With gestures, the conductor beats the pulse, cues entrances, and shapes the character of each passage. Much of the work happens in rehearsals, when the conductor decides with the musicians how the piece will be realized. The movement of the hands and the baton is only the visible part of a larger process.

Before the concert, the orchestra tunes. The oboe usually gives the note A, and the other instruments adjust to it, starting with the woodwinds, then the brass, and finally the strings. The oboe is chosen for its penetrating sound and relatively stable pitch. To understand why a reference note is needed, read about musical tuning and the role of reference pitches.

Size and repertoire

The size of the orchestra changes with the repertoire. A classical orchestra, from the time of Haydn and Mozart, had fewer players, with few brass and limited percussion. In the nineteenth century, works by composers such as Beethoven, Berlioz, and Wagner enlarged the number of instruments, and the orchestra came to include trombones, tuba, piccolo, English horn, and varied percussion.

Chamber orchestras bring together fewer musicians, without a large brass section, and suit works from the Baroque and classical periods. To distinguish this format from bands and from smaller groups, the article on the differences among band, orchestra, and chamber ensemble clarifies each case.

The program and listening to a concert

A symphonic concert usually follows a predictable structure: a short opening piece, a concerto for soloist and orchestra, and a symphony. In the concerto, the soloist stands at the front, beside the conductor, and the orchestra converses with the soloist. Between the movements of a symphony, the audience traditionally does not applaud, because the work is understood as a continuous whole.

Knowing the makeup of the orchestra helps you listen closely. By noticing when the strings give way to the woodwinds, when the brass enter to reinforce a climax, and when the percussion punctuates a phrase, the listener follows the architecture of the work and not only the melody.

Reading the stage before the music starts

You can learn a great deal just by looking at the stage before the first note. A large brass section and extra percussion suggest a late Romantic or twentieth-century score; a small string group with few winds points to Baroque or early classical music. The number of harps, the presence of a piano or celesta, or an unusual instrument such as a bass drum set off to one side all hint at what is coming. Program notes often list the forces required, and matching that list to the seats on stage turns the wait before a concert into part of the listening.

Where to go from here

The next time you attend a concert, notice where each section sits and try to identify the tone colors by ear before looking. Watch the concertmaster and the oboe during the tuning and hear how the reference note spreads through the ensemble. To lock in what you have learned about sections, seating, and roles, test your knowledge in the quiz.