TRIO

musical composition for three instruments or voices, or a performing group of three voices or instruments. The name trio originally referred to contrapuntal writing for three voices or parts, as in the trio sonata (q.v.) of Baroque music. The name trio soon came to denote the middle (B) section of a dance movement that occurs in ABA form, the trio being the section that occurs between the principal dance (whether a minuet, scherzo, or so on) and its repetition. This type of trio was so called because it was customary to score the middle (B) movement for three instruments, typically two oboes and a bassoon. J.S. Bach followed this practice in the second (trio) section of his First Brandenburg Concerto. The trio section's purpose was to provide a light relief or change of mood. In the Classical period, the name trio came to denote a piece of chamber music written for three players. The most important of such trio combinations was the piano trioa piece written for piano, violin, and cello. Joseph Haydn composed 31 piano trios, and the form developed through W.A. Mozart, climaxing in trios written by Ludwig van Beethoven (notably his Ghost Trio, Opus 70; and Archduke Trio, Opus 97) and Franz Schubert (Opuses 99 and 100). The string trio is usually for violin, viola, and cello, though Haydn's 20 string trios are for two violins and cello. Luigi Boccherini, Mozart, and Beethoven wrote string trios, but the form was subsequently neglected until it was revived by modernist composers in the 20th century. Other trio combinations usually include one or more wind instruments, such as Johannes Brahms's Opus 40 for horn, violin, and piano and his Opus 114 for clarinet, cello, and piano.