Musical Intervals: Their Names
An interval is the tonal distance between two notes. It is often useful to think of the distances between notes rather than the notes themselves. It is the relative position of notes that gives a scale, chord or melody its sound.
A system of referring to these distances was developed that uses the Major Scale (a.k.a. Diatonic Scale) as the basis for the names given to these intervals. For instance, the third note of the Major Scale is two whole steps from the root (the first note of the scale). Therefore, the interval distance between two notes separated by two whole steps is called a major third. Similarly, the sixth note of the Major Scale is 4-1/2 whole steps from the first note. Therefore, the interval between two notes separated by 4-1/2 whole steps is called a major sixth.
Names of Intervals
The list of interval names above shows the official names for these intervals. However, the ways these intervals are actually referred to can be confusing. Musicians will often refer to an interval in a generic way without being specific if the interval is major, minor, augmented, or diminished. Musicians will talk about “the third.” You have to understand the context to know if they are talking about a minor 3rd or a major third. The same thing happens with “the seventh.”
Major vs. minor
The 2nd, 3rd, and 6th intervals can be major or minor. The interval before a major interval can be called minor or flatted as in a minor 3rd or a flatted third which are the same interval. A minor 7th and a flatted 7th are the same.
The 4th and 5th are called perfect. The reason why they are “perfect” has to do with their special harmonic ratios. That is an interesting topic but not important here. At any rate, the interval a semitone higher than a perfect fourth is called an augmented fourth. You might also hear someone call it a “sharp four.” The perfect fifth can be either augmented or diminished a half step. Likewise, the intervals a semitone lower and higher than a perfect fifth might be called a “flatted 5th” and “sharp five” respectively.
You know you are a real musician when you hear someone ask, “What’s the flat five in the key of A-flat?” and you can answer, “That would be E natural.” One of the benefits of knowing music theory is that you can communicate with other musicians. Unfortunately, musicians can be down-right sloppy with their terms but if you know your intervals, you’ll be able to understand what they mean.