Answer:
During the Middle Ages, vocal music was predominantly monophonic, with a single melody line that was typically sung by a soloist or choir. In the Renaissance period, vocal music became more polyphonic, with multiple independent melody lines that were sung simultaneously. In the Baroque period, vocal music continued to evolve, with the development of new forms such as opera and the cantata. In the Classical and Romantic periods, vocal music became even more expressive and emotional, with the development of new forms such as the art song and the lied. In the 20th century, vocal music continued to evolve, with the development of new styles and techniques. Overall, the evolution of vocal music from the Middle Ages to postmodernism has been characterized by a gradual increase in complexity and expressiveness, as well as the incorporation of new musical materials and techniques.