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ウィキペディア フリーな encyclopedia
In classical music from Western culture, a seventh is a musical interval encompassing seven staff positions, and the minor seventh is one of two commonly occurring sevenths. It is qualified as minor because it is the smaller of the two: the minor seventh spans ten semitones, the major seventh eleven. For example, the interval from A to G is a minor seventh, as the note G lies ten semitones above A, and there are seven staff positions from A to G. Diminished and augmented sevenths span the same number of staff positions, but consist of a different number of semitones (nine and twelve).
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/1/1f/Minor_seventh_on_C.png/320px-Minor_seventh_on_C.png)
![Minor seventh on C.mid](http://upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Loudspeaker.svg/12px-Loudspeaker.svg.png)
![Greater just minor seventh on C.mid](http://upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Loudspeaker.svg/12px-Loudspeaker.svg.png)
Minor seventh intervals are rarely featured in melodies (and especially in their openings) but occur more often than major sevenths. The best-known example, in part due to its frequent use in theory classes, is found between the first two words of the phrase "There's a place for us" in the song "Somewhere" in West Side Story.[1] Another well-known example occurs between the first two notes of the introduction to the main theme music from Star Trek: The Original Series theme.[2]
The most common occurrence of the minor seventh is built on the root of the prevailing key's dominant triad, producing the all-important dominant seventh chord.
Consonance and dissonance are relative, depending on context, the minor seventh being defined as a dissonance requiring resolution to a consonance.[3]