An interval represents the distance between two pitches. The interval-search convention for Themefinder uses the traditional interval naming style in music theory. Each interval consists of three features:
- the interval direction (ascending or descending),
- the interval quality: Perfect, minor, Major, Augmented, and diminished.
- the diatonic interval size: second=2, fifth=5, etc.
The diatonic interval size is the same as counting the spacing between two white notes on the keyboard. Going from C up to G is a distance of 5: (1) C, (2) D, (3) E, (4) F, (5) G.
Interval quality naming conventions have a long history. Most classically trained musicians know the conventions, but it takes a bit of effort to learn for the first time. There are two classes of intervals: perfect and imperfect.
Perfect intervals are the set of intervals which were determined to be consonant up though the 15th(?) century. This set of intervals includes unisons (1), fourths (4), fifths (5), and the octave (8) plus their octave transpositions. A simple way of defining this set is the unison, the fifth, plus all inversions and octave tranpositions.
Imperfect intervals are intervals which are not as pure as the perfect intervals. They fall into two groups depending on their accepted consonance/dissonance quality:
- consonant imperfect intervals:
- Major/minor third, Major/minor sixth.
- dissonant imperfect intervals:
- Major/minor second, Major/minor seventh.
The major scale is made up of Major and Perfect intervals in relation to the tonic note. Here is a list of these intervals:
The minor scale is made up of Major, Minor and Perfect intervals in relation to the tonic note. Here is a list of these intervals:
