Which composer was a notable figure in the integration of emotional expression in music?

The composer who stands out for his integration of emotional expression in music is Machaut. He was a pivotal figure in the development of the Ars Nova style in the 14th century, which introduced greater complexity in rhythm and harmony, allowing for more nuanced emotional communication in vocal music. Machaut's use of the motet and secular song forms demonstrates a keen awareness of text and emotion, enabling a more profound connection between the music and its lyrical content. This was particularly evident in his virelais and rondeaux, where the interplay between poetic expression and musical structure created rich emotional experiences.

In contrast, the other composers mentioned—Leonin, Hildegard, and Palestrina—while significant in their own rights, primarily focused on different aspects of music. Leonin is notable for his contributions to early polyphony and doesn't emphasize emotional expression in the same way. Hildegard's works, while deeply spiritual and often expressing individual emotion, are primarily characterized by their mystical qualities rather than a broader integration of emotional expression as understood in later traditions. Palestrina, known for his clear text setting and conservative style, focused on counterpoint and clarity rather than direct emotional expression. Thus, Machaut remains a key figure for his role in bringing emotional depth