"Now I'd like to talk about what happens in one of the other genres. Because there is one genre in which sonata form is modified a good bit in order to suit the essential nature of it. That's the concerto. Who plays in a concerto? A symphony orchestra and a soloist," said Dr. Broyles as he started his explanation of the role of the concerto in the classic repertoire.
After explaining why we wait so long for the soloist to begin playing with the orchestra in many classic period concertos, Dr. Broyles went on to explain an improvisational element of music in the classic period: the cadenza--and why soloists often end their cadenza with a trill.