Machaut, Guillaume de, ma SHOH, gee YOHM duh (1300?-1377), was a medieval French composer and poet. His best-known composition is his Mass, the earliest complete Mass for four voices by a single composer. He also wrote many French and Latin songs for one to four voices. The songs have elegant and expressive melodies, and often use offbeat rhythmic effects known as syncopation. Machaut's songs follow strict poetic forms. A typical song has its chief melody sung by the highest voice, accompanied by one or two voices or instruments in the tenor range. Machaut also wrote many songs for only one voice, like the songs of the poet-musicians called troubadours (see Troubadour).