Last time, we went through the definition of pitches. In this article, we will get insights into a concept that infers the difference in pitch between two notes: interval.
As the name suggests, intervals indicate the melodic distance between two notes. Regularly, in music, intervals are measured by semitones, and there are 5 types of intervals: major, minor, perfect, augmented, and diminished; each helps describe a certain interval degree. The table below shows how some basic intervals are named within an octave.
| Semitones | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tones | 0 | 0.5 | 1 | 1.5 | 2 | 2.5 | 3 | 3.5 | 4 | 4.5 | 5 | 5.5 | 6 |
| First | Perf | Aug | |||||||||||
| Second | Dim | Min | Maj | Aug | |||||||||
| Third | Dim | Min | Maj | Aug | |||||||||
| Fourth | Dim | Perf | Aug | ||||||||||
| Fifth | Dim | Perf | Aug | ||||||||||
| Sixth | Dim | Min | Maj | Aug | |||||||||
| Seventh | Dim | Min | Maj | Aug | |||||||||
| Eighth | Dim | Perf |
(Dim: diminished; Min: minor, Maj: major; Aug: augmented; Perf: perfect)
Note: A perfect 1st is called "a unison", while a perfect 8th is called "an octave"
For example, the interval between C and A (in the same octave), which are 9 semitones (or 4.5 tones) apart, is a “major sixth”. As depicted, only the first, fourth, fifth, and eighth intervals have the “perfect” quality, while the others—the second, third, sixth, and seventh intervals—can either be “major” or “minor”. The characteristic “augmented” illustrates that the interval is a semitone higher than the normal “perfect” or “major” interval; conversely, “diminished” shows that it is a semitone lower than “perfect” or “minor”.
Well, before continuing, have you ever wondered why, although E# and F are considered the same note, the interval from C to E# is called “augmented third” while the interval from C to F is called “perfect fourth”? It may sound confusing, but the purpose of this is to indicate the degree to which the two notes primarily differ: in this situation, E is the third degree of a C scale, while F is the fourth. As you can see in the chart, there are certain intervals that have two names, which depend on the label of either note of the interval.
Now, let’s get to another concept: interval inversions. The interval from a C to a D is a major second, right? Then what about from D to C? It’s a minor seventh. This is called interval inversion. To get the name of the inverted interval, the interval’s quality is switched, except for perfect: minor to major, augmented to diminished, and vice versa, and the new degree is nine (9) subtracted by the former degree.
You may wonder how intervals beyond an octave are named. Those intervals are regarded as “compound intervals”, and just like inverted intervals, they can be figured out using simple intervals. Take, for instance, C4 and F#5. Firstly, we will remove any octaves in between the notes to make them a simple interval - in this case, C4 and F#5 - then, name the interval as usual - augmented fourth here. We would add the number-of-octaves-removed multiplied by 7 to the former degree - now it becomes eleventh. Tada! Now we know that the interval from C4 to F#5 is an augmented eleventh.
Intervals are a foundational part of music: they help define the gap between two certain notes, and, later on, help us build scales, chords, and songs. The characteristics of intervals-major, minor, augmented, diminished, and perfect-all have meanings behind their names, but we will get to this later as we dig deeper into the concepts of consonance, dissonance, and chords. Inverted and compound intervals are a little trickier to work out, but all it takes is some math (not rocket science though *wink*).
