Orchestration

Orchestration is the art and craft of writing music for an orchestra or similar ensemble, like a concert band, or of adapting a piece originally written for a different setup—such as a solo piano work—so that an orchestra can perform it. Often called instrumentation, it is the process of deciding which instruments play which musical parts, such as the melody, bassline, or harmony.

In classical music, composers traditionally handled their own orchestration. Over time, it became recognized as a distinct skill and profession, though today most classical composers still orchestrate their own work. Notable exceptions include Maurice Ravel’s orchestration of Modest Mussorgsky’s solo piano piece *Pictures at an Exhibition* and Malcolm Arnold’s orchestration of William Walton’s String Quartet in A minor, which became Walton’s *Sonata for Strings*.

In musical theatre, film, and other commercial media, orchestrators and arrangers are commonly employed. This is often due to tight deadlines or because the composer’s training may not cover orchestration in depth. The orchestrator’s role in film varies widely, depending on the composer’s needs and skills. In musical theatre, the composer typically produces a piano/vocal score, then hires an orchestrator to create the full instrumental parts for the pit orchestra. In jazz big bands, a composer may write a lead sheet (melody and chords), and orchestrators or arrangers develop it into parts for saxophones, trumpets, trombones, and the rhythm section (bass, piano/guitar/Hammond organ, drums). However, many big band composers arrange their own music, much like their classical counterparts.

As a profession, an orchestrator is a trained specialist who assigns instruments to an orchestra or ensemble from a composer’s work, or adapts music from another medium for orchestra. Orchestrators may work in theatre, film, or recording studios, and some teach at colleges, conservatories, or universities. Their training varies: most hold a Bachelor of Music, Master of Music, or an artist’s diploma. Those teaching at postsecondary institutions may need a master’s or doctorate (Ph.D. or D.M.A.). In the 2010s, as institutional ratings increasingly factor in the percentage of faculty with terminal or doctoral degrees, more schools require such credentials. However, orchestrators hired by film, theatre, or other organizations may be chosen solely on experience, even without academic degrees.

In practice, orchestration refers to how instruments are used to convey musical elements like melody, harmony, or rhythm. For example, a C major chord consists of the notes C, E, and G. If these notes are held for a full measure, the orchestrator must decide which instruments play them and in what register. Woodwinds and brass are monophonic—each can play only one note at a time—so a composer might assign each note of the chord to a separate clarinet or trumpet. Strings, piano, harp, and pitched percussion are polyphonic and can play multiple notes. For a string section playing a C major chord, the cellos and basses might take the low C, violas the G, second violins a high E, and first violins an E an octave higher. If only the violins play the chord, the second violins could take a low C, while the first violins play a double stop of G (open string) and E.

Notes can also be placed in different registers (e.g., transposed down for basses), doubled in the same or different octaves, and given varying dynamics. The choice of instruments, registers, and dynamics shapes the overall tone color. A C major chord played fortissimo by trumpets and trombones in their upper registers sounds bright; the same chord played sul tasto by cellos and double basses, doubled by bassoons and bass clarinet, might sound heavy and dark. This approach applies not only to chords but also to melodies or even single notes. And orchestration in this sense is not limited to orchestras—a composer might orchestrate the same chord for a woodwind quintet, string quartet, or concert band, each offering different timbres and colors. A melody is orchestrated similarly: the composer or orchestrator conceives it (perhaps at the piano or organ) and then decides which instrument will carry it.