Computers and music have been linked since the earliest days of the mainframe, when giant machines controlled primitive synthesizers. Recently, however, a significant advancement has taken place in the field of computer music with the development of software that can not only transcribe polyphonic music in real time, but can also play back complex harmonies alongside human performers. For instance, at the annual Music Information Retrieval Exchange (MIREX) competition, Christopher Raphael of Indiana University demonstrated a system that can understand live music well enough to accompany a musician.