Final answer:
Charles Ives's compositional style was influenced by his experiences with New York Philharmonic concerts, fiddlers at country dances, harmonium accompanying church hymns, and two marching bands performing different tunes in a parade, contributing to his unique approach.
Step-by-step explanation:
The influential elements of Charles Ives's compositional style include experiential and environmental factors from his life. New York Philharmonic concerts exposed Ives to a variety of classical music forms and styles, and the sophisticated orchestral techniques certainly played a role in shaping his own complex compositions. Moreover, his experience with fiddlers at country dances would have acquainted him with traditional American tunes and folk elements that appeared in his music. The role of harmonium accompanying church hymns that Ives played at services contributed to the incorporation of religious and spiritual themes, as well as traditional hymn tunes in his work. Lastly, the auditory spectacle of two marching bands performing different tunes in a parade aligns with Ives's fondness for polytonality and simultaneous performance of multiple, contrasting musical themes. These experiences collectively influenced Ives's groundbreaking approach to composition.