Abstract: A method and apparatus for producing a musical output is disclosed. The method and apparatus permit the creation, storage and retrieval of a first data structure representing a musical piece. The first data structure includes digital music information that represent musical notes of the musical piece. A second data structure can be created, stored and retrieved as well. The second data structure can include information different from the first data structure and the second data structure can be used to modify the first data structure and to produce a modified musical output. The apparatus and method also permit repeated use of the first data structure.