Final answer:
Folk music has had a strong influence on Western classical music, particularly in the form of Opera. It is a reflection of local cultural influences and was integrated into the Western classical tradition, particularly during the Romantic era.
Step-by-step explanation:
The strong influence on Western classical music, especially in form, comes from Folk music, which significantly shaped Opera. Folk music is intrinsic to a community's tradition, created by local musicians and embedded with cultural nuances that resonate with the identity of the audience. When composers in the Western classical tradition drew upon these rich musical folk traditions, it gave rise to operas that often incorporated native melodies, harmonies, and rhythms into their compositions, thereby influencing the structure and content of classical music. Despite the varying influences, classical music retains its distinct language, structure, and style through various expressions including the symphony, concerto, and sonata, as well as other forms like ballet and choral music.
During the Romantic era, classical music saw an evolution despite retaining its classical roots. Composers of the time, like Beethoven, were revered and emulated. They continued to follow the established rules of rhythm, melody, harmony, and other musical fundamentals that were created during the Classical period. Folk influences found their way into the popular music of this era through the manifestation of local conditions and ethnic background, molding the landscape of music further. This evolution was, in part, possible due to the rise of the middle class and their demand for public concerts, increasing the audience base for classical and folk-inspired classical works.