La 'Evolving Tonality' di Joseph Yasser: una teoria microtonale tra le correnti dello sperimentalismo newyorchese

Abstract

In 1932 the Polish-Jewish theorist and organist Joseph Yasser (1893-1981) published in New York A Theory of Evolving Tonality, in which he described a 19-tone equal temperament. He predicted the use of this microtonal system in Western music as a future development of the 12-tone equal temperament. The nucleus of Yasser's book is the reconstruction of an historical process – the evolving tonality – that leeds from the pentatonic system (infra-diatonic, 5 tones per octave) to the diatonic (7 tones per octave) till the chromatic (supra-diatonic, 12 tones per octave). In the music of his contemporaries, like Skrjabin, Debussy and Schoenberg, Yasser recognizes the affirmation of the chromatic scale as a system of 12 indipendent tones. The next step will be the introduction of 7 new auxiliaries tones, that will create a new microchromatic scale (supra-diatonic scale, 12 + 7 tones per octave). The indirect influence on Yasser's theory of microtonal experiments in New York during the 1920s is supposed. Furthermore, in this essay other 19-tone equal temperament experiences are put in relashionship with the evolving tonality.