Equal temperament

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Equal temperament is a musical tuning system in which all intervals are approximated by multiples of a single interval. The most common equal temperament represents the octave as 12 exactly equal semitones. The 12-note chromatic scale employs a semitone ratio equal to the 12th root of 2 ( 2 12 {\textstyle {\sqrt[{12}]{2}}} ≈ 1.05946). Equalizing the semitones in this way causes other intervals to deviate slightly from their "pure" sounds; the fourths and fifths produced by this method are closer to their just intonation than the thirds and sixths are. Equal temperament has been the predominant tuning system of Western music since the 20th century. It is also used in other cultures.

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