Development of a session system with acoustic instruments

In this paper the authors describe the development of a session system whic h follows human performance and creates an improvisational accompaniment. O ne of the features of this system is that it can use acoustic instruments s uch as pianos and guitars instead of MIDI instruments which are common in c onventional session systems. In a session system complex sounds such as cho rds must be input and the input musical information must be analyzed in rea l time. The authors' system can recognize chord names in real time through signal processing that takes advantage of the fact that instrument sounds a re harmonics, while observing the restriction that detailed musical informa tion such as the pitch of the sounds comprising a chord or the accuracy of the duration of sound production are not analyzed. The recognition rate for four-note chords using thirds was shown in an experiment to exceed 95% usi ng this method. In addition, the function which extracts the smallest repet ition unit from a piece of music automatically allows for a session system that does not need to know the score beforehand. (C) 2001 Scripta Technica.