Trio Sonata

Two melodic lines over one bass, three written parts played by four musicians

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A trio sonata gives three written parts to four players, two melodic lines each taken by an instrument, with a bass line and a keyboard filling in the harmony.

Origins and era

It took shape in Italy in the early seventeenth century. Corelli fixed two uses in Rome, the church sonata built on fugue and slow-fast contrasts, the chamber sonata built on allemande, courante, sarabande and gigue. By the late seventeenth century it had spread across Europe, with Purcell in London and Buxtehude in Lübeck. Bach's BWV 1039 and the Musical Offering pushed the writing to its limit, after which the string quartet and the duo sonata took over its function.

What you hear

The scoring is two violins, or flute and oboe, plus a bass string instrument and a keyboard, and the score has only three lines. The texture is two equally weighted treble lines, the theme handed from one part to the other, while the bass moves only when the harmony changes and keeps the beat clear. Three to five movements follow a slow-fast pattern, church sonatas opening with imitation, chamber sonatas named after dances. How the bass is written shapes the whole impression, since Corelli keeps it on the roots of the harmony while French composers let broken chords join the motivic play. Listen for the two treble lines first, then decide whether the bass walks or stands still, and whether the two lines are truly equal or the first violin always leads.

Key figures

Corelli's Op. 1 to Op. 4 are the models, Purcell set English counterpoint inside the Italian frame, Telemann and Bach made the genre a staple of publishing and teaching, and Tartini brought a soloist's taste for ornament into the first part.

Lineage

It grows from the Renaissance instrumental canzona and Venetian polychoral writing and leads to the string quartet, the duo sonata and later chamber music, while its fugal sections became a keyboard genre of their own.

Common misunderstandings

A trio sonata is not played by three people, since it usually takes four, and the two melodic lines may be shared by one instrument and a keyboard's right hand. Nor is it a concerto for three, because a concerto separates tutti from soloists while all three lines here stay equal.

Sources

• The New Grove Dictionary of Music and Musicians, 2nd ed., entry Trio Sonata, 用于核对体裁定义与年代
• Richard Taruskin, The Oxford History of Western Music, Vol. 2, 用于核对意大利与英国的传播路线

Used for fact-checking only; all prose is original.