Debbie Schiller, age 14, of Prescott, Ariz. for her question:

JUST WHAT IS CHAMBER MUSIC?

Chamber music is instrumental music for an ensemble of musicians, ranging from two to about 10, with one player for each part and all parts of equal importance. Such music was originally meant for private performance, the term "chamber music" meaning simply music neither for dance nor for church, theater or other public performance.

Chamber music, from about 1750, has been principally for string quartet, although string quintets as well as duets, trios, quartets and quartet of four stringed instruments plus a piano or wind instrument have also been popular. A string quartet is made up of two violins, one viola and one cello.

Public concerts of chamber music were initiated only in the 19th century.

Secular music, or non church music, was typically for small instrumental ensembles during the Middle Ages and the Renaissance. There were also many compositions for instruments and voice, with voice pieces in three, four and five parts.

In the baroque era, from about 1600 to 1750, the musical texture of chamber music was that of high melody lines supported by a basso continuo    a bass melody played, for example, by cello or bassoon, with harmonies filled in by a lute, harpsichord or organ.

The most prominent 17th century composer of trio and solo sonatas was the Italian Arcangelo Corelli, whose works influenced the chamber music of the English composer Henry Purcell and, later, that of French composer Francois Couperin, the German English composer George Frederick Handel and Johann Sebastian Bach.

In the classical era, from 1750 to about 1820, the Austrian composer Joseph Haydn developed chamber music as a style distinct from other ensemble music. Haydn's music influenced Wolfgang Amadeus Mozart. Ludwig van Beethoven greatly expanded the dimension of the string quartet while preserving its intimate character.

Chamber music in the romantic era, from about 1820 to 1900, was developed primarily by composers whose romantic temperament was mingled with a classical inclination    such as Franz Schubert from Austria and Johannes Brahms from Germany.

Two trends emerged in 20th century chamber music. Classical genres such as the string quartet were infused with contemporary idioms and techniques in works of the French composers Claude Debussy and Maurice Ravel, the Hungarian Bela Bartok and Austrians Arnold Schoenberg and Anion von Webern.

Chamber ensembles of varied composition    often including voices, harp, guitar and wind and percussion instruments    became a primary vehicle for new music by composers such as Schoenberg, Webern, the Russian born Igor Stravinsky and the French Pierre Boulez.

Important as a predecessor of the new style were Viennese light music genres such as the divertimento and serenade.