Final answer:
Before the 19th century, the church and aristocracy were key institutions supporting music and composers, providing financial backing and commissioning works. Technological advancements in the Romantic era led to a shift from court patronage to public concerts, reflecting the rising middle class's interest in music.
Step-by-step explanation:
Before the early 19th century, the primary institutions that supported music and the livelihood of composers like Beethoven were the church and the aristocracy. These institutions provided financial support and venues for performance as well as commissioning works for religious services and courtly entertainment. The funding from these patrons enabled the creation of compositions that have endured as cultural milestones. The church played a key role, especially during the 16th century, in the consolidation of polyphonic practice and development of vocal music, with composers such as Palestrina and William Byrd emerging from its tutelage. Meanwhile, aristocratic courts, particularly in Italy by the end of the 16th century, became vibrant centers of musical activity, furthering the careers of prestigious composers and music educators.
However, with the advent of the Romantic era, typified by Beethoven's later works, there was a shift from courtly patronage to public concerts and festival performances, largely as a result of the rise of the middle class and their demand for music as part of a broader cultural experience. This era also saw technological improvements, such as those to wind instruments and the piano, which facilitated the development of a new musical language and expanded orchestral possibilities.