By:Robert Rawlins and Nor Eddine Bahha


To understand any melodic or harmonic discussion, one must understand ingervals. An interval measures the space between two pitches. The smallest interval in Wester music is the semitone or half step (either name may be used). This is the distance from one key to the next on the piano, for intance from C to C.

The next-to smallest interval is the tone, or whole step. This is the distance between notes that are two keys apart on the piano. For instance, from C to D is a whole step. The semitone and tone form the basis for measurement of larger intervals.

Interval measurements have two parts: quantity and quality. The quantity, or numeric value, is determined by the musical alphabet: C D E F G A B. For example, the interval formed by the notes C and G will always be some type of 5th, regardless of the quality of C or G (flat or shap).

Intervals are used so often in describing chords and scales that they are sometimes named in an extremely abbreviated way. Learn to recognize these variations in interval names.

  • Perfect and major intervals are implied by no mention of their quality al all: 5 for P5 (perfect 5th),7 for M7 (major 7th), etc.
  • The Word “Sharp”, or the Sharp symbol is often used instead of “augmented” (or its abbreviations, “aug” or “+”).
  • The Word “flat” or the flat symbol is often used instead of “min” or “m”
  • When a perfect interval (1, 4, 5 or 8) becomes diminished, it may be written with one flat instead of dim or d, or the diminished symbol.
  • When a major interval (2, 3, 6, 7) becomes minor, it too is often written with two flats instead of min or m, for instance 2 instead of
  • When a major interval becomes diminished, it can be written with two flats instead of dim or d,for instance 7 instead of dim7 or d7.


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