10. The musical score playing method according to claim 8 , wherein said changing further comprises changing the note values of the grouped notes when the playing time of the grouped notes is shorter than the reference time of one beat and the number of sixteenth notes in the group is 3, or the number of thirty-second notes is 5 or 7.
10. The musical score playing method according to claim 8 , wherein said changing further comprises changing the note values of the grouped notes when the playing time of the grouped notes is shorter than the reference time of one beat and the number of sixteenth notes in the group is 3, or the number of thirty-second notes is 5 or 7. 12. The musical score playing method according to claim 10 , wherein said changing further comprises changing a total note value for the number of grouped notes to a duration obtained by multiplying a total duration of the note values of the grouped notes by a number set in advance in accordance with the number of notes grouped.