Sergei Vladimirovich Protopopov (Russian: Сергей Владимирович Протопопов; 2 April 1893, Moscow – 14 December 1954, Moscow) was a Russian avant-garde composer and music theorist. Sergei Protopopov was the chief proponent of a compositional strategy devised by Kiev-based theorist Boleslav L. Yavorsky. Published in book form as Structure of Musical Speech in 1908, the technique used modal rhythm as its basis, in combination with the uncertain harmonic pull of the tritone. Read more on Last.fm