What is the form of a musical piece called when it has two alternating sections, section a and section b?

Who wrote the famous messe de mister dame

Where does middle c get it’s name? a. it sits in the middle of a brass clef b. it sits in the middle of the grand staff c. if sits in the middle of the alto clef d.its sits in the middle of the treble clef

Jazz evolved slowly from a number of different musical sources..true or false