Final answer:
Art music is defined as music that requires formal, specialized training, distinguishing it from folk, popular, and traditional music styles.
Step-by-step explanation:
Art music can best be defined as music that is learned formally with specialized training. Unlike folk, popular, or traditional music, art music typically refers to classical traditions which embody the formal instruction and expertise of musicianship. Folk music is often characterized by its homemade nature, produced by unschooled musicians for local audiences. Popular music is designed to appeal to a wide audience and doesn't necessarily require formal education. Traditional music usually refers to genres preserved over time within certain cultures.