This invention relates to an electronic musical instrument having an automatic ensemble function.
Among musical performance styles is included an ensemble performance, such as duet, trio and quartet. In this performance style a plurality of tones are simultaneously produced. Thus, usually, in addition to a melody, one or a plurality of tones having a predetermined interval relation with respect to the melody are simultaneously produced for the purpose of improving the feeling of the melody. Thus, for a music having a tendency of becoming monophonic, the ensemble performance thickens the tone thus eliminating the monophonic feeling, and where the ensemble performance is used at a bridge or release portion, the content of the music can be enriched. Such ensemble performance, however, requires a relatively high degree of skill so that this performance can not be enjoyed by all performers. Notwithstanding a desire of development of a musical instrument or an electronic musical instrument capable of automatically effecting the ensemble performance, the prior art electronic musical instrument or an automatic performance device could not automatically perform the desired ensemble performance.
Thus, there has been developed no automatic performance device capable of producing ensemble notes, nor has been impossible to modify the construction of an existing automatic performance device so as to perform the ensemble performance. A musical instrument has already been know in which a plurality of tones can be produced simultaneously by depressing only one key. For example, such musical instrument can, by depressing a key of a musical tone, produce a plurality of tones that is chords having predetermined interval relations with respect to the musical tone. Such musical instrument, however, is constructed to make automatic performance of the chords so that it has a musical effect different from that of the ensemble performance. For this reason even when an automatic performance device of chords is used for the ensemble performance, it is impossible to provide the effect of the true ensemble performance. Because, with the automatic performance device for chords, only the tones having always the same interval relation are produced irrespective of the note of the depressed key.
On the other hand, the basic principle of the ensemble performance lies in the simultaneous production of a plurality of tones having interval relations of predetermined degrees among the notes of the diatonic scale of the tonality key of the music. For this reason even for the same degree numbers, there may arise a case wherein the intervals differ by a semi-tone for different degree notes in the same tonality key. Thus, even though the third intervals have a same degree number, there are two different kinds i.e. a major third and a minor third depending on the notes. In the same manner, for the same note the ensemble note will be a major third or a minor third apart there from depending on the tonality keys. Not only in the cases of the major interval and the minor interval, but also in the cases of the fourth or fifth intervals, a difference between a perfect interval and an augmented interval or a diminished interval occurs. However, in the prior art chord automatic performance device, as the interval relationship is always determined by the type of the chords it is impossible to discriminate the major interval from the minor interval or to descriminate the perfect interval from the augmented or diminished interval meaning that it is impossible to play correct ensemble performance.