Septimal minor third

In 24-tone equal temperament five quarter tones approximate the septimal minor third at 250 cents (Playⓘ).

In the meantone era the interval made its appearance as the alternative minor third in remote keys, under the name augmented second.

[8] Twelve-tone equal temperament (12-TET), as commonly used in Western music, does not provide a good approximation for this interval, and quarter tones (24-TET) do not match it well either.

Several non-Western and just intonation tunings, such as the 43-tone scale developed by Harry Partch, do feature the (exact) septimal minor third.

The phenomenon of hearing this root pitch is evident in the following sound file, which uses a pure sine wave.

Septimal minor third on C
Origin of large and small seconds and thirds in harmonic series. [ 2 ]