GROUND BASS

also called Basso Ostinato (Italian: obstinate bass), in music, a short, recurring melodic pattern in the bass part of a composition, serving as the principal unifying factor of the composition. Early instances are found in 13th-century French motets as well as 15th-century cantus firmus dances where a skeletal melody served as a cantus firmus, or fixed theme. In the 16th century the practice of composing counterpoint (interwoven melodies) upon a repeated bass pattern became popular in Italy and Spain. Well-known grounds, such as the passamezzo antico, romanesca, folia (all closely related), ruggiero, and passamezzo moderno, took their names from popular dances spread throughout Europe. All such grounds involved unchanging harmonic patterns that provided ideal frameworks for improvisation. Closely allied to the harmonic ground is the melodic ground favoured in the 17th century. Here, the bass harmony commonly varies with each repetition of its melodic pattern, and the upper parts may overlap the ground, which may be transposed to new pitch levels during the course of a piece. Although particularly characteristic of the Baroque era, the ground bass had a more or less continuous history in European music from the 16th to the 20th century. The improvisational potential of ground bass patterns has also been extensively exploited in American jazz.