Minor third

What it means

The minor third comprises three semitones; its pure frequency ratio is 6:5. Together with the major third it decides the mode: a triad with a minor third above the root is minor, one with a major third major. The difference amounts to a single semitone and changes the character of a sonority completely.

Musical use

As an imperfect consonance the minor third may be led in parallel; in the diatonic scale, major and minor thirds alternate, so that parallel thirds are alternately major and minor and thereby stay within the key.

From the stacking of minor thirds several sonorities of particular constitution arise. Two on top of one another yield the diminished triad, three on top of one another the diminished seventh chord — a sonority that divides the octave evenly and therefore has no unambiguous root. Precisely this makes it useful for enharmonic reinterpretations and remote modulations.

Melodically the minor third is a comfortable, easily singable leap; it belongs to the first intervals that children hit securely and shapes countless call and children's songs. In inversion it becomes the major sixth.

For intonation it holds that the minor third is narrower in equal temperament than the pure one; in free ensemble playing it is therefore taken rather wide — the reverse of the major third.

The minor third is the determining interval of minor and arises between the root and the third of the minor triad. But it is also found in major, between the third and the fifth of the major triad. In just tuning it has the ratio 6:5. Many children's songs and call motifs move at the distance of a falling minor third.

Performance practice

Practise distinguishing major and minor third deliberately; recognizing major and minor rests on it, and it is the most profitable single ear-training exercise. Intonate the minor third in the minor chord rather high. And with parallel thirds, match attack, length, and dynamics so that they act as one sound.