There are several terms used to describe the texture of music, referring to the density and number of parts. Monophonic music consists of a single line. Homophonic music generally refers to multiple parts that are not independent, rhythmically or melodically. A chorale or hymn is an example. These might also be referred to as homorhythmic. A single melodic line with an accompaniment may also be referred to as homophonic.
Polyphony is music with two or more parts, each with an independent melody, while sharing a harmonic and rhythmic context. Counterpoint is the art of combining two or more melodic lines in structured polyphony. The word counterpoint is derived from the Latin phrase “Punctum Contra Punctum,” which means “note against note.”
In imitative counterpoint, the parts share motives and complement each other. Melodic ideas are passed between parts, often in the form of a dialog. In a canon, consistent repetition between parts is used exclusively. A canon is defined by the rhythmic duration between the two parts, and the intervallic distance between them. The first part is called the dux, and the second part the comes. A round is a form of canon in which a complete phrase is the duration between entries, the interval is typically an octave, and it may be sung as many times as there are voices.
In the 16th century most Western music of record was modal. This means that the melodies constructed using the pitches found in the ecclesiastical modes. The counterpoint (CP) was written to complement an existing Cantus Firmus (CF), which was typically drawn from a Gregorian Chant or early sacred melody. Species counterpoint defines the ratio of notes in the counterpoint compared to the cantus firmus. The slower moving part is the cantus firmus. Each species has a different ratio or particular features.
First species is 1:1
Second species is 2:1
Third species is 4:1
Fourth species is the use of suspensions and syncopations (rhythmically offset 2:1)
Fifth species is florid counterpoint, a mixture of all species
Composers of species counterpoint adhered to a rather strict set of rules for writing melodies in both the counterpoint (CP) and in the cantus firmus (CF). These rules, or guidelines, were codified in the Gradus ad Parnassum, a treatise written by Johann Joseph Fux and published in 1725. Fux sets forth the guidelines in a series of dialogues, using the music of Palestrina (1525-1594) as the foundation. In addition to Palestrina, Orlando di Lasso (1532-1594) was a prolific composer who conformed to the style of the time. Spanish composer Tomas Victoria (1548-1611) was another notable figure of the time, as was William Byrd (1543-1623) in England.
Modal species counterpoint persisted throughout most of the 16th century, and it was supplanted by major-minor tonality around the beginning of the 17th century. Tonal counterpoint has been practiced since the 18th century by most composers in one form or another. The music of J. S. Bach is often associated with counterpoint, since he was instrumental in establishing it as a primary texture in much of his music. In the Classical and early Romantic periods counterpoint was not the dominant texture, but composers such as Mozart and Brahms wrote contrapuntal music. In the early 20th century Post-Tonal counterpoint was developed. It applied many of the basic relationships found in historical polyphony, but not in a framework of functional harmony. Two of the better known practitioners were Paul Hindemith and Bela Bartok. Later in the 20th century composers such as Steve Reich, Terry Riley, Phillip Glass and John Adams wrote a repetitive form of counterpoint. They were dubbed “Minimalists.”