Major seventh chordIn music, a major seventh chord is a seventh chord in which the third is a major third above the root and the seventh is a major seventh above the root. The major seventh chord, sometimes also called a Delta chord, can be written as maj7, M7, , 7, etc. The "7" does not have to be superscripted, but if it is, then any alterations, added tones, or omissions are usually also superscripted. For example, the major seventh chord built on C, commonly written as Cmaj7, has pitches C–E–G–B: { \override Score.
Interval ratioIn music, an interval ratio is a ratio of the frequencies of the pitches in a musical interval. For example, a just perfect fifth (for example C to G) is 3:2 (), 1.5, and may be approximated by an equal tempered perfect fifth () which is 27/12 (about 1.498). If the A above middle C is 440 Hz, the perfect fifth above it would be E, at (440*1.5=) 660 Hz, while the equal tempered E5 is 659.255 Hz.
Musical temperamentIn musical tuning, a temperament is a tuning system that slightly compromises the pure intervals of just intonation to meet other requirements. Most modern Western musical instruments are tuned in the equal temperament system. Tempering is the process of altering the size of an interval by making it narrower or wider than pure. "Any plan that describes the adjustments to the sizes of some or all of the twelve fifth intervals in the circle of fifths so that they accommodate pure octaves and produce certain sizes of major thirds is called a temperament.
Fifth (chord)In music, the fifth factor of a chord is the note or pitch that is the fifth scale degree, counting the root or tonal center. When the fifth is the bass note, or lowest note, of the expressed chord, the chord is in second inversion . Conventionally, the fifth is second in importance to the root, with the fifth being perfect in all primary triads (I, IV, V and i, iv, v). In jazz chords and theory however, the fifth is often omitted, or assumed, in preference for the chord quality determining third and chord extensions and additions.
DitoneIn music, a ditone (ditonus, from δίτονος, "of two tones") is the interval of a major third. The size of a ditone varies according to the sizes of the two tones of which it is compounded. The largest is the Pythagorean ditone, with a ratio of 81:64, also called a comma-redundant major third; the smallest is the interval with a ratio of 100:81, also called a comma-deficient major third. The Pythagorean ditone is the major third in Pythagorean tuning, which has an interval ratio of 81:64, which is 407.82 cents.
Minor seventh chordIn music, a minor seventh chord is a seventh chord composed of a root note, together with a minor third, a perfect fifth, and a minor seventh (1, 3, 5, 7). For example, the minor seventh chord built on C, commonly written as C–7, has pitches C–E–G–B: { \new Staff \with{ \magnifyStaff #1.5 } \relative c' { \override Score.TimeSignature #'stencil = ##f 1 } } A seventh chord with a minor third, perfect fifth, and minor seventh is commonly called a minor seventh chord, but also sometimes a minor/minor seventh chord to distinguish it from the minor/major seventh chord discussed below.
