"Invocatio" for chamber orchestra
Doctor of Musical Arts
Invocatio is scored for the following instruments: piccolo, flute, 2 oboes, 2 clarinets (2nd doubling bass clarinet), 2 bassoons (2nd doubling contrabassoon), 2 horns, trumpet, 2 percussionists, piano (doubling celesta), and strings. The duration is ca. seven minutes. The material that forms the basis of the piece is exclusively derived from two pitch cell collections. These are based on the monograms of the composers Johann Sebastian Bach and Dmitri Shostakovich. The pitches come from the German musical spelling of the composers' surnames: B - A - C - H and D - Ess - C - H (equivalent to B-flat - A - C - B-natural and D - E-flat - C - B, respectively, in English music terminology). Invocatio may be regarded as consisting of two contrasting ideas, both presented already in mm. 1--5. This dual process evolves throughout the course of the work, and may also be described as a dynamic between "ightness" (mm. 1--3) and "darkness" (mm. 4--5). This process is ultimately resolved in the final section, beginning in m. 108. Transpositions are basically limited to the Shostakovich tetra-cell, while the original pitch class collection of the Bach is almost always retained. The primary transpositions of the Shostakovich are: A - B-flat - C - D-flat, F-sharp - G - A - B-flat, and C - D-flat - E-flat - E-natural . Both tetra-cells are closely related in their respective pitch class sets: [0,1,2,3] (Bach) and [0,1,3,4,] (Shostakovich), thus facilitating the juxtaposition and merging of the two tetra-cells. The Shostakovich cell, when transposed at the tritone, yields the octatonic scale. Fragments of the octatonic scale occur throughout the piece. A final synthesis of the two tetra-cells is attained at the very end of the piece: in the final two bars, both monograms are simultaneously presented, the Shostakovich cell now stated in its original pitch class form ( D - E-flat - C - B).