"Musical expressivity is intimately associated with subtle dynamic changes--slight variations in volume between one note and the next--which help shape and make meaningful the phrases. Daniel Gottlob Turk was among the few theorists who recognized and described this subtlety."
"Performance Practice and Musical Expressivity,"
Performance Practice Review:
1, Article 2.
Available at: http://scholarship.claremont.edu/ppr/vol8/iss1/2