Text: interval. [0] the distance between two pitches or notes. Intervals may be measured in a number of ways; e.g., by counting the number of semitones, subtracting frequencies, etc. Counting semitones is used in set theory. However, the most common method is by counting letter names; e.g. C,D,E,F includes 4 letters--thus, C to F is called a fourth and is always a fourth, no matter how the notes may be altered by sharps or flats. This is called the "general size" of the interval. However, each general interval may have several "specific sizes"; e.g. a third could be major, minor, diminished, augmented, etc. The specific size is determined by 1. the general size, and 2. the number of semitones it contains. Solomons Musical Glossary

See Also:

Source: