Schenker, Heinrich (hĪnˈrĭkh shĕngkˈər) [key], 1868–1935, Austro-Polish music theorist. Educated at the Vienna Conservatory, he devoted his life to teaching and research. Schenker developed the concept of structural levels and coherence in tonal music. He conceived of all tonal pieces as generated from a basic cell, the triad (major or minor chord). The interest and singularity of a composition were ascribed to the imagination and consistency with which the composer elaborated the triad into a complete piece. Schenker's theories have been successfully applied to nontonal music and influenced 20th-century theoreticians.