PSEUDOOCTAVE
Pseudo-octave
A pseudo-octave, pseudooctave, or paradoxical octave in music is an interval whose frequency ratio is not 2:1, that of the octave, but is perceived or treated as equivalent to this ratio, and whose pitches are considered equivalent to each other as with octave equivalency. When used as a basis for an equal temperament, the pseudo-octave may also be called the Interval of Equivalence, the Repeat Ratio, and the nonoctave.The above text is a snippet from Wikipedia: Pseudo-octave
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