System and method for applying a role-and register-preserving harmonic transformation to musical pitches

摘要

This invention relates to a system and method for altering the harmonic referent of segments of a music composition while maintaining the register of the musical segments and their conformity to a harmonic rule-base. By combining the three novel notions of a "role-preserving" transformation "shape-preserving" transformation, and a "register" preserving transformation, a novel operation enabled by the present invention can be described. Essentially, the invention allows a pitch to be moved from one harmonic context to another. The pitches are then constrained to take on values that have the same harmonic function as their corresponding original pitches, while remaining, as much as possible, within the same register as their corresponding original pitches. Secondly, when a group of pitches are moved together as a melody, the operation can preserve not only the function and register of the pitches but the shape of the melody. Many instruments in the orchestra have a timbre that varies quite dramatically from the bottom to the top of their pitch range. A transformation which can preserve the register can be helpful, when applied to the parts of an orchestrated score, in keeping the timbral qualities intended by the original arranger. Further, when considering instruments with relatively limited pitch-ranges, preserving register is important to help ensure that the transformed part can still be realized on the desired instrument.