Learning Objectives
- Learn about interval qualities (perfect, major, minor, augmented, and diminished).
- Identify the two general categories of intervals.
Intervals III: Interval Quality
Interval Quality
The second step in identifying an interval (after you have determined its numeric size) is to determine its quality. Interval quality describes the character or color of an interval. Consider, for example, the following two melodic intervals:
| Major Sixth | Minor Sixth |
Both of these intervals are sixths, with the same numeric size (6). But they sound quite different. Listen to them and compare their qualities. The first interval is called a major sixth. The second one is called a minor sixth. You may have noticed that the minor sixth sounds "sadder" or "darker" than the major sixth, which tends to sound "brighter" and more "cheerful."
What is it that determines an interval's unique quality? Looking again at the sixths above, you will see that the principal difference between them is that the minor sixth (C to A♭) is a half-step smaller than the major sixth (C to A). That is, there are 9 semitones in a major sixth and only 8 semitones in a minor sixth. That is what gives them their different qualities, making one of them sound major and the other one minor. In other words, the quality of an interval is determined by the number of half-steps (or semitones) that it contains. Intervals with the same numeric size may have different qualities, depending on the number of semitones they contain.
Interval Qualities
Musicians have developed a number of terms to describe the quality or character of musical intervals. Major and minor are just two of the five types of qualities that intervals may have. The others are perfect, augmented, and diminished. The following chart provides all five interval qualities along with their common abbreviations.
| Quality | Abbreviation |
|---|---|
| perfect | P |
| major | M |
| minor | m |
| augmented | A, aug, or + |
| diminished | d, dim, or o |
| Interval Qualities | |
These quality abbreviations are often grouped with a numeric interval size to create a full interval name. For example, M6 would indicate a major sixth, m3 would be a minor third, and P5 would be a perfect fifth.
Interval Categories
Intervals can also be divided into two general categories or "families": (1) the perfect intervals, and (2) the major/minor intervals. The other interval qualities (augmented and diminished) can be thought of as variants of these two main interval categories. In the lessons that follow, we will first discuss the perfect family of intervals, then the major/minor family of intervals.