Trio (It., from tre, formed in imitation of duo)
- Erich Schwandt
(It., from tre, formed in imitation of duo)
(1) A piece of music for three players. The commonest types are the Piano trio (piano, violin, cello) and the String trio (violin, viola, cello); see also Chamber music, Trio sonata and (for vocal music) Terzet.
(2) In the 18th century, the term ‘trio’ was applied to an instrumental piece for three obbligato voices, without further accompaniment, in strict style. Many such pieces belong to the realm of academic music, being used by theorists to demonstrate rules of counterpoint and composition. There are, however, trios of this kind in the keyboard music of J.S. Bach, notably in his organ sonatas and his sinfonias (or three-part inventions), where all three voices are equally important and all three are continuously engaged in working out the musical ideas. The canons of the Goldberg Variations, except that at the 9th, are trios. Trios are also prominent in his organ chorales, where the variety in treating various combinations of voices is striking....