A Jommelli is a variant of a clausula cantizans (also called a ⑦–① cadence or, in Gjerdingen’s term, a Comma (Gjerdingen (2007), p. 155–157)).
While ⑦ of a clausula cantizans is usually realized as a sixth chord or 6/5 chord in a variable number of parts, ⑦ of a Jommelli is set in a three-part texture with a diminished fifth in the middle voice and by a minor or diminished seventh in the upper voice, depending on the mode. These intervals usually descend simultaneously stepwise above ① to the third and the fifth, respectively. In major, the seventh on ⑦ is minor, a sonority that Niccolò Jommelli (1714–1774) uses often there and results in a specific cadenza that Gjerdingen named after this composer (Gjerdingen (2007), p. 158).
See also Clausulæ.
See also Comma.
Select Bibliography
Gjerdingen, Robert O. Music in the Galant Style (New York: Oxford University Press, 2007).