Just Intonation--A system of tuning scales by using simple mathematical ratios of tone frequencies for the purest harmonic tone intervals. Thus the octave of A 440Hz is A 880Hz, a ratio of 2/1; the fifth is 660Hz, a ratio of 3/2; the fourth is 586.67Hz, a ratio of 4/3; and so on.

Pythagorean Tuning--A system of tuning scales, created by ancient Greek mathematician Pythagoreas, by successive descending and ascending fifths, and reducing those resulting tones outside the octave to within the octave. The major pentatonic scale is produced by 4 ascending fifths, while the suspended pentatonic scale is produced by 2 ascending and 2 descending fitths. The musical fourth could also be used to create the same scales.

Pentatonic Scale--A scale of 5 tones. Penta is Greek for 5. Two common pentatonic scales are the major pentatonic scale and natural minor pentatonic scale. The major pentatonic scale consists of the first, second, major third, fifth, and sixth degrees of the diatonic scale; and is found in many musical cultures around the world. The natural minor pentatonic scale consists of the first, minor third, foruth, fifth, and flat seventh degrees of the diatonic scale; and is relative to the major pentatonic scale. A third suspended pentatonic scale consists of the first, second, fourth, fifth, and flat seventh degrees of the diatonic scale; and is only modally different from the major pentatonic scale, but symmetrical in nature.

Anhemitonic--Without halftones. Most common pentatonic scales are anhemitonic as are the major pentatonic scale, the natural minor pentatonic scale, and the suspended pentatonic scale, along with their 2 other modal kindred. Anhemitonic scales are considered most consonant and more pleasing and soothing to listen to.

Hemitonic--With halftones. The C Major 9 Chord of Summer Wind Chime and Summer Simmer Wind Chime is composed of the first, third, fifth, major seventh, octave, and ninth (a second raised an octave), creating a halftone between the major seventh and octave. Essentially this is a major seventh pentatonic scale, unrelated modally to the major pentatonic scale, except that the sixth of the major pentatonic scale has been raised a wholetone to create the major seventh pentatonic scale. The Blues Scale adds the blue flat fifth to the natural minor pentatonic scale to produce a a hexatonic (six tones) and hemitonic scale with 2 sequential halftones. Hemitonic scales are more dissonant but most expressive and interesting to listen to.

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