In music, the septimal whole tone is the musical interval exactly or approximately equal to a 8/7 ratio of frequencies. It is about 231 cents wide. The term septimal refers to the fact that it utilizes the seventh harmonic of the harmonic series. The cent is a logarithmic unit of measure used for musical intervals. ... Pitched musical instruments are usually based on a harmonic oscillator such as a string or a column of air. ...

This interval does not fit easily into equally-tempered tuning systems. The standard 12 equal temperament used in most western music does not come close to this interval. The 19 equal temperament offers a closer, but still poor match for this interval, but it does not distinguish between this interval and the septimal minor third, which it has a better fit for. The 22 equal temperament distinguishes between these two intervals, but it still matches the septimal whole tone poorly. The 31 equal temperament is the smallest widely used equal temperament that matches this interval closely. In music, 19 equal temperament, called 19-tet, 19-edo, or 19-et, is the scale derived by dividing the octave into 19 equally large steps. ... In music, the septimal minor third, also called the subminor third (by eg Helmholtz) is the musical interval exactly or approximately equal to a 7/6 ratio of frequencies. ... In music, 22 equal temperament, called 22-tet, 22-edo, or 22-et, is the scale derived by dividing the octave into 22 equally large steps. ... In music, 31 equal temperament, called 31-tet, 31-edo, or 31-et, is the scale derived by dividing the octave into 31 equally large steps. ...