What is the musical form of the trecento madrigal?

Singers change the timbre of a sound by changing the

a. formation of the tongue and mouth b. amount of air passing through the throat c. amount of tension of the vocal cords d. relaxing and tightening their diaphragms e. All of these choices

An early composer of polyphonic music was

a. Henry VIII b. Pérotin c. Hildegard of Bingen d. Pythagoras e. Thomas Aquinas