ABSTRACT
An interval is the difference in pitch between two tones. That difference can be measured in many ways. The most common way musicians identify intervals is through a two-part designation consisting of a numeric value and a qualifying term. Intervals having different numeric values and qualifiers can sound identical. That is, they can comprise an identical number of half steps. Intervals are classified in ways other than numeric value and quality. A simple interval is one that is an octave or smaller, whereas a compound interval exceeds the octave. Compound intervals are traditionally reduced to simple intervals for ease of reference. Intervals may also be classified as consonant or dissonant. Consonance refers to sounds that suggest a feeling of stability or repose. Dissonance denotes sounds that suggest tension or unrest. Intervals were classified by the theorist Franco of Cologne in the thirteenth century.
