Monophony. Monophony is the simplest of musical textures, and is
one of the earliest historical musical forms. Plainchant, or
Gregorian chant, is a commonly cited example of monophony, and was
popular in Italy, Ireland, Spain and France. While 9th century
plainchant incorporated extra voices in parallel fifths, Byzantine
chant, Armenian chant, and Mozarabic chant are all strictly
monophonic.