This invention relates to an electronic musical instrument capable of producing chord tones in consonant note intervals.
Generally, an electronic musical instrument is tuned in an equally tempered scale so that it is easy to modulate or transpose to other keys or to make ensemble performance with other musical instruments. However, when the electronic musical instrument is thus tuned with the equally tempered scale, such chord tones as major triad chord tones are not produced in perfect consonant intervals so that it constitutes one of the factors that disturb harmony. For example, when major triad chord tones are produced by a just intonation scale, the frequency ratio of the root note tone to the major third note tone is just "4:5", and the frequency ratio of the root note tone to the perfect fifth note tone is "2:3" and accordingly "4:6". On the other hand, when the major triad chord tones are produced with the equally tempered scale, the frequency ratio of the root note to the major third note is "4:5.03984"Thus, the pitch of the major note in the equally tempered scale becomes higher by 14 cents than that of the major third note in the just intonation scale. Furthermore, when major triad chord tones are produced in an equally tempered scale, the frequency ratio of the root note to the perfect fifth note is "4:5.993228". Thus, the pitch of the perfect fifth note in the equally tempered scale is lower by 2 cents than that of the perfect fifth note, in a just intonation scale. As a consequence, where chord tones are produced in a just intonation scale, clear tones can be produced with consonant intervals. On the other hand, were chord tones are produced in an equally tempered scale, the tones become a bit unharmonic.