Polish-born Russian-American organist, conductor, and musicologist; b. Lodz, April 16, 1893; d. N.Y., Sept. 6, 1981. Yasser studied at the Moscow Conservatory, graduating in 1917 as an organist. After several years of teaching organ in Moscow and Siberia, he reached Shanghai in 1921 and conducted a choral society there.

Yasser subsequently emigrated to the U.S. in 1923, serving as organist at Temple Rodeph Sholom in NY. from 1929 to 1960. He became interested in how scales are formed, writing a famous theory book, A Theory of Evolving Tonality, in 1932. He also contributed several articles to Musical Quarterly dealing with QUARTAL HARMONY, which were subsequently published in a book in 1938.