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A neutral seventh is a musical interval wider than a minor seventh but narrower than a major seventh . Four distinct intervals may be termed neutral sevenths: * A ''septimal neutral seventh'' has a ratio of 64:35 or about 1045 cents. * The just ''undecimal neutral seventh'' has a ratio of 11:6 between the frequencies of the two tones,〔Andrew Horner, Lydia Ayres (2002). ''Cooking with Csound: Woodwind and Brass Recipes'', p.131. ISBN 0-89579-507-8.〕 or about 1049 cents . Alternately, 13:7〔 or about 1071.7 cents. * A ''tridecimal neutral seventh'' has a ratio of 24:13 between the frequencies of the two tones, or about 1061 cents. This is the largest neutral seventh, and occurs infrequently in music, as little music utilizes the 13th harmonic. * An ''equal-tempered neutral seventh'' is characterized by a difference in 1050 cents between the two tones, a hair larger than the 11:6 ratio, and exactly half of an equal-tempered major thirteenth (octave plus major sixth). These intervals are all within about 12 cents and are difficult for most people to distinguish. Neutral sevenths are roughly a quarter tone sharp from 12 equal temperament minor sevenths and a quarter tone flat from 12-ET major sevenths. In just intonation, as well as in tunings such as 31-ET, 41-ET, or 72-ET, which more closely approximate just intonation, the intervals are closer together. A neutral seventh can be formed by stacking a neutral third together with a perfect fifth. Based on its positioning in the harmonic series, the undecimal neutral third implies a root one perfect fifth below the lower of the two notes. ==See also== * List of musical intervals * List of pitch intervals * Microtonal music 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「neutral seventh」の詳細全文を読む スポンサード リンク
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