Many Baroque concertos are structured in a form known as
ritornello form.
Ritornello form was prevalent in early opera before being adopted in instrumental music. It is a recurring passage in Baroque music for orchestras or chorus. The first and final movement of a solo concerto or aria may be in "
ritornello form", in which the
ritornello is the opening theme, always played by tuitti, which returns in whole or in part and in different keys throughout the movement, in which particulars the form differs from the rondo.
In this form, stable instrumental interludes, known as
ritornellos (literally, "the little thing that returns"), alternated with verses of singing over a continuo accompaniment. The verse and chorus structure of modern popular music derives from this form.
Ritornello form was favoured by Bach, Vivaldi, Telemann and Handel in chamber works, vocal pieces and, most prominently, in the solo concerto in a 'tuitti-solo-tuitti-solo-tuitti' pattern in which the
ritornello, the tuitti section, functions as a refrain or chorus while the solo sections may expand upon the short melodic lines of the tuitti. At the end of the movement the entire
ritornello returns in the home key. J.S. Bach's Brandenburg Concertos offer excellent examples. In opera seria, the ritornello functioned as the main structural support for the da capo aria, in which it was successively repeated.
The final section of a fourteenth century madrigal had previously been called the
ritornello and a similar technique had been employed by Giovanni Gabrieli in his 16th century motets. The instrumental interludes in early Baroque operas were also termed
ritornelli.
Ritornello construction faded with the advent of the new sonata form but renewed interest in the 20th century.
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