The harmonic seventh interval, also known as the septimal minor seventh,[2][3]
or subminor seventh,[4][5][6]
is one with an exact 7:4 ratio[7]
(about 969 cents).[8]
This is somewhat narrower than and is, "particularly sweet",[9]
"sweeter in quality" than an "ordinary"[10]just minor seventh, which has an intonation ratio of 9:5[11]
(about 1018 cents).
The harmonic seventh arises from the harmonic series as the interval between the fourth harmonic (second octave of the fundamental) and the seventh harmonic; in that octave, harmonics 4, 5, 6, and 7 constitute the four notes (in order) of a purely consonant major chord (root position) with an added minor seventh (or augmented sixth, depending on the tuning system used).
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Haluska, Jan (2003). "Harmonic seventh". The Mathematical Theory of Tone Systems. CRC Press. p. xxiii. ISBN0-8247-4714-3.
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Horner, Andrew; Ayres, Lydia (2002). Cooking with Csound: Woodwind and brass recipes. A-R Editions. p. 131. ISBN0-89579-507-8.
^Bosanquet, R.H.M. (1876). An Elementary Treatise on Musical Intervals and Temperament. Houten, NL: Diapason Press. pp. 41–42. ISBN90-70907-12-7.
^
Brabner, John H.F. (1884). The National Encyclopædia. Vol. 13. London, UK. p. 135 – via Google books.{{cite book}}: CS1 maint: location missing publisher (link)