" A composer from this country used its folk idioms in his Excursions for piano and wrote a violin concerto with a perpetuum mobile third movement.
A serialist composer from this country argued that serious music is too difficult for the layperson to understand in the article "Who Cares If You Listen?" It's not the UK, but like Ralph Vaughan Williams, another composer from this country wrote A Sea Symphony, as well as a fourth symphony subtitled "Requiem." A composer from this country used its folk idioms in his Excursions for piano and wrote a violin concerto with a perpetuum mobile third movement. That composer's Opus 11 is a string quartet whose second movement was arranged to create a melancholic piece for string orchestra to which he later added a choral setting of the Agnus Dei. That piece is the Adagio for Strings. For 10 points, name this country home to Milton Babbitt, Howard Hanson and Samuel Barber.
A serialist composer from this country argued that serious music is too difficult for the layperson to understand in the article "Who Cares If You Listen?
the United States of America [accept obvious equivalents]