1. A music modification system, comprising: a computer, a music element library, wherein the music element library comprises at least one database of techniques or algorithms that provide measures and representations of harmonic, melodic, rhythmic and contrapuntal material, and wherein the measures or representations comprise an harmonic reduction of a model music piece, and at least one of a harmonic reduction of an input music piece, a note list split into instrumental parts, a note list split into instrumental parts and further split into contrapuntal voices, a note list that has been split into voices and further split into melodic segments, a rhythmic analysis, an analysis of contrapuntal configurations across voices, an analysis of individual contrapuntal voices or a combination thereof; at least one part-score database, a software code that executes a music modification system on the computer, wherein the music modification system accesses or manipulates the information in the music element library and accesses the at least one part-score database, and a graphical or audio user interface that is coupled to the computer.