Joseph Yasser

Joseph Yasser (April 16, 1893 – September 6, 1981) was a Russian–American organist, music theorist, author, and musicologist. An influential figure who established a handful of musical institutions, Yasser is noted for his 1932 publication, A Theory of Evolving Tonality. He was active until his death at age 88 in 1981. Yasser was married but had no children.

Early life and career

For comparison, a 19 equal temperament keyboard, after Woolhouse (1835) and Easley Blackwood Jr. with seven white diatonic keys and twelve black keys

Yasser was born in Łódź, Poland (then part of the Russian Empire), on April 16, 1893. He studied piano in Moscow with renowned pianist-cum-composer Jacob Weinberg and from 1912 to 1917 enrolled at the Moscow Conservatory, graduating with honors. In 1918 Yasser succeeded B. Sabaneev as leader of the school's organ department. Particularly interested in the Chinese organ, Yasser continued as a Chinese music lecturer in the United States. He served as organist and choir director at Congregation Rodeph Sholom from 1929 to 1960. However, he may be best known as the author of A Theory of Evolving Tonality (1932) and advocate of progressive equal temperaments; Yasser wrote music in 19 equal temperament. He supported the use of the musical interval measurements, namely the decitone, centitone, and millitone.

In a series of articles from 1937 to 1938, which were later compiled into a book titled Medieval Quartal Harmony, published by the American Library of Musicology, he proposed the implementation of a system "harmonizing pentatonic melodies" based upon the perfect fourth interval.