Renaissance era, notated secular and sacred music survives in quantity, including vocal and instrumental works and mixed vocal/instrumental works. A wide range of musical styles and genres flourished during the Renaissance, including masses, motets, madrigals, chansons, accompanied songs, instrumental dances, and many others. Beginning in the late 20th century, numerous early music ensembles were formed. Ensembles specializing in music of the Renaissance era give concert tours and make recordings, using modern reproductions of historical instruments and using singing and performing styles which musicologists believe were used during the era. Overview One of the most pronounced features of early Renaissance European art music was the increasing reliance on the interval of the third and its inversion, the sixth (in the Middle Ages, thirds and sixths had been considered dissonances, and only perfect intervals were treated as consonances: the perfect fourth the perfect fifth, the octave, and the unison). Polyphony – the use of multiple, independent melodic lines, performed simultaneously – became increasingly elaborate throughout the 14th century, with highly independent voices (both in vocal music and in instrumental music). The beginning of the 15th century showed simplification, with the composers often striving for smoothness in the melodic parts. This was possible because of a greatly increased vocal range in music – in the Middle Ages, the narrow range made necessary frequent crossing of parts, thus requiring a greater contrast between them to distinguish the different parts. The modal (as opposed to tonal, also known as "musical key", an approach developed in the subsequent Baroque music era, c. 1600–1750) characteristics of Renaissance music began to break down towards the end of the period with the increased use of root motions of fifths or fourths (see the "circle of fifths" for details). An example of a chord progression in which the chord roots move by the interval of a fourth would be the chord progression, in the key of C Major: "D minor/G Major/C Major" (these are all triads; three-note chords). The movement from the D minor chord to the G Major chord is an interval of a perfect fourth. The movement from the G Major chord to the C Major chord is also an interval of a perfect fourth. This later developed into one of the defining characteristics of tonality during the Baroque era. The main characteristics of Renaissance music are: Music based on modes. Richer texture, with four or more independent