Abstract: The number of chords belonging to a first chord group is decreased to less than the number of chords belonging to a second chord group. In a first detection mode, when a first determining unit determines that a state of key depressed does not correspond to any chord in a first chord group, a previously selected chord is continuously determined. Accordingly, even if a chord detection is performed on a change of melody point by point, the number of chords substantially detected is decreased. This decreases the number of changes in accompaniment, thus stabilizing a playback of the accompaniment.

Abstract: The number of chords belonging to a first chord group is decreased to less than the number of chords belonging to a second chord group. In a first detection mode, when a first determining unit determines that a state of key depressed does not correspond to any chord in a first chord group, a previously selected chord is continuously determined. Accordingly, even if a chord detection is performed on a change of melody point by point, the number of chords substantially detected is decreased. This decreases the number of changes in accompaniment, thus stabilizing a playback of the accompaniment.

Abstract: The ROM 101 stores a chord scale note table composed of a plurality of scale by 12 notes starting from a chord tone in which C note is given as a root note and arranging a chord scale note as an inverted form of a chord in which the note is given as the lowest note. Where there is any change in chord at a beginning note of a phrase, or while phrase is played, notes are replaced to suppress note jump by using the chord scale note table. Where time from the previous key-on to the current key-on is in excess of a predetermined time, the note jump will not be suppressed.

Abstract: The ROM 101 stores a chord scale note table composed of a plurality of scale by 12 notes starting from a chord tone in which C note is given as a root note and arranging a chord scale note as an inverted form of a chord in which the note is given as the lowest note. Where there is any change in chord at a beginning note of a phrase, or while phrase is played, notes are replaced to suppress note jump by using the chord scale note table. Where time from the previous key-on to the current key-on is in excess of a predetermined time, the note jump will not be suppressed.

Abstract: An automatic accompaniment apparatus includes a storage section for storing a plurality of accompaniment patterns. Each of the plurality of accompaniment patterns corresponds to an automatic accompaniment data. One of the plurality of accompaniment patterns is selected by a selecting section based on an input specifying data, and then one of the plurality of accompaniment data corresponding to the selected accompaniment pattern is selected. An accompaniment sound signal generating section generates an accompaniment sound signal based on the selected automatic accompaniment data by the selecting section.