The Simple Intervals
As previously mentioned, there are five distinct types of interval qualities: major, minor, perfect, diminished, and augmented. The distance of an interval always consists of the quality first, followed by the numerical measure of how many notes you are traveling, for example, major sixth. The simple intervals—major, minor, and perfect—are presented first, followed by diminished and augmented intervals in the next section.
Major intervals apply only to distances of seconds, thirds, sixths, and sevenths. A quick trick to spell any major interval is to look at the major scale being used. For example, if you wanted to find out what a major third was from the note E, you could spell the scale, name the third note of the E major scale, and that would be your answer. Many musicians use this method to spell intervals and scales.
The other way to figure out an interval is to look at the distance in half steps (or whole steps). This method precludes knowing the scale (which this book doesn't officially get to until next chapter). Table 2.1 below presents all the major intervals and their intervallic distances.
TABLE 2.1: MAJOR INTERVALS
That's all there is to major intervals!
Minor intervals are closely related to major intervals, as they also only exist as seconds, thirds, sixths, and sevenths. So, what's the difference between a major and a minor interval? Simply, a minor interval is exactly one half step smaller than a major interval. Look at table 2.2 on minor intervals and compare it to table 2.1 on the major intervals.
TABLE 2.2: MINOR INTERVALS
You can name any major interval simply by looking at a major scale and counting. This works for the minor scale, but it's not perfect. If you spell out the minor scale, you do, in fact, get the minor third, minor sixth, and minor seventh, but beware of the second. A minor scale's second note is a major second from the root. If you need to measure a minor second, just remember that a minor second is the smallest interval in music: the half step.
Minor intervals are always exactly one half step lower than their major counterparts. So, if you have to name a minor interval and you're fast at the major intervals, simply lower any major interval exactly one half step and you will be there. FIGURE 2.16 below shows how this works.
FIGURE 2.16 Major Intervals to Minor
See, that isn't so bad! Just remember that major intervals are the larger of the two intervals when you compare major and minor intervals.
So far, the logic to naming interval quality has made sense: Major intervals come from major scales, and minor intervals (all except one) come from the minor scale. Now you come to perfect intervals, and you may be wondering what is so perfect about them. Here is a brief history lesson.
Strengthen your vocabulary! Instead of talking about half and whole steps, call them by their proper names. A half step is a minor second and a whole step is a major second.
As music was evolving, most music was monophonic, meaning that only one line was sung or played at a time. When musicians became daring enough to add a second line of music, they considered only certain intervals consonant and those were the ones that could be used.
In the early days of polyphony, fourths and fifths were commonly used, so perfect seemed to fit because they almost never sounded bad. To modern ears, fourths and fifths don't always sound as nice as thirds or sixths do, but that's just a matter of taste.
Back to the intervals! Perfect intervals encompass the following distances: unison (no distance at all), fourth, fifth, and octave.
Perfect intervals are fairly easy to spell because all the perfect intervals appear in both the major and the minor scales, so no matter what you are more comfortable spelling in, you'll find all the perfect intervals there. If you're up for counting in steps, look at table 2.3.
Table 2.3: PERFECT INTERVALS
The term octave has the root oct like octagon. Oct, of course, is the prefix indicating eight, and an octave is the distance spanning eight notes. More important, an octave is the same letter name repeated at a higher part of the musical spectrum.
In contrast to major intervals that can be made into minor intervals by simply lowering them a half step, the perfect intervals are stuck. If you do anything to a perfect interval (flat or sharp one of the notes), you are changing the interval type away from being perfect. It always becomes something else. What it actually becomes is something discussed in the next section.
See, this isn't that bad. Intervals are fairly concrete and have an absolute distance; you can name them based on those parameters. Remember, though, naming an interval includes two parts: quality and distance. You have two more qualities to explore: augmented and diminished.