Performance information of one or more accompaniment parts is extracted from original performance information. Arranged accompaniment performance information is created using, in accordance with a predetermined arranging condition, only any one or more of pitch names included in the extracted accompaniment performance information. The predetermined arranging condition comprises instructing that any of chord component notes be thinned out in an identified chord progression, and arranged accompaniment performance information is created by thinning out an accompaniment note of a pitch name corresponding to the chord component note having been instructed to be thinned out. Another predetermined arranging condition comprises setting a ratio between chords and arpeggios in one or more measures, and a combination of chords and arpeggios in the extracted accompaniment part performance information is changed so that a ratio between chords and arpeggios in one or more measures in the extracted accompaniment performance information assumes the set ratio.

In a synthesizer 1, the highest note number is set from the allowed Oct width and the lowest note number of a sound production part in a setting table 11e, and if the note number of an Arp note memory 12b is not between the lowest note number and the highest note number, the note number of one octave unit is added to or subtracted from the note number of the Arp note memory 12b. Consequently, the note number of the Arp note memory 12b is corrected to the pitch range between the lowest note number and the highest note number, and thus can be corrected to the sound production pitch range of the timbre of the sound production part, and arpeggios can be outputted using sounds that are more appropriate for an instrument of said timbre.

Provided are an electronic musical instrument, a processing execution method, and a processing execution program capable of quickly performing registration to a key group based on key depression from key depression, and special processing based on keys registered to the key group. In a case where the depressed position of a key 2a is between a determination start position D3 and a determination end position D4, the key 2a is registered to a key group. Registration of the key 2a to the key group can be quickly determined by only confirming the depressed position of the key 2a. In a case where a key 2a registered to the key group reaches a sound generation start position Ds, and the registration number in the key group at that point is two or more, a musical note with a special tone based on that key 2a is generated. Therefore, the time lag from the registration of the key 2a to the key group to the start of sound generation based on the key 2a registered to the key group is minimized, making it possible to quickly register a key 2a to the key group based on key depression from key depression, and generate a musical note based on the key 2a registered to the key group.