What is organum?

• A. The earliest form of polyphonic music developed from adding voices to plainchant, initially in parallel fifths or fourths and later more freely
• B. A modern electronic music genre
• C. A form of string quartet ensemble
• D. A type of vocal improvisation in jazz

Answer: (A)

Organum is the earliest form of polyphonic music. It grew by adding one or more voices to a preexisting plainchant, so you hear two or more lines at once while the chant remains clear. In the beginning, the added voice often moved in parallel with the chant, creating intervals of fourths or fifths, which gives that sturdy, hollow sense of early polyphony. Over time, composers pushed toward more independence for the added line, so the voices didn’t always move together in lockstep. This historical move—from adding voices to plainchant to creating more freely moving, interwoven lines—defines organum.

That description distinguishes organum from the other options, which point to modern electronic music, a string quartet ensemble, or jazz vocal improvisation—contexts that belong to much later musical styles rather than medieval polyphony.