Everything has intervals. Runners measure their success by the interval between their start and finish time. In math, an interval is the distance between two numbers (integers for you math wizzes). Although music is often seen as artsy and not based on anything concrete, music is actually very much based on math and today we’re going to look at an example of that.

In music, an interval is the distance between two notes and is expressed based on scale degrees. Let’s look at how to identify the basic intervals.

Let’s start with identifying the interval between C and E. If we count up from C (count C as #1) there are three scale degrees between C and E (C,D,E equals 3). For this reason, the interval between C and E is a third (3rd). What is the interval between D and A? If you count D as #1 and count up to A, there are 5 scale degrees between D and A which makes the interval a fifth (5th)

Nothing in music is that simple, though. There are different types of these intervals. There are Major 3rds, minor 3rds, Perfect 4ths, and minor 6ths to name a few but it’s not as complicated as it sounds. The amount of half steps between each interval defines the specific type of interval. Let’s look at a few.
What is the interval between C and Eb? Let’s count the half steps (C to Db, Db to D, D to Eb equals 3 half steps) 3 half steps equals a minor 3rd. Try this one on your own. What is the interval between D and A? Remember to count the half steps. The easiest way to do that is to count them on a piano. Then figure out the name: (“m” equals minor, “M” equals Major, “P” equals Perfect)

Did you say that the interval was a Perfect 5th? If you did, you got it right! Good job!
Before we call this lesson complete, two more quick facts: The reason that the fourths and fifths are called Perfect has to do with some advanced concepts grounded in acoustics but the short answer is that a perfect interval is more pure and stable than major intervals.

There are also diminished and augmented intervals as well as tritones. All of these advanced intervals will be addressed in later articles. For now, practice identifying the basic intervals and you will be well on your way to understanding the important points.

All music theory (the study of how music is constructed) is based on identifying intervals so put some work in to this lesson before moving on to more advanced topics.

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One note played alone is termed a “unison.” Two notes played simultaneously  or adjacently are called “intervals.” Three or more notes in combination are termed “chords.”

So if C and D are played simultanously the distance between them is called “a 2nd.” C and E would be a 3rd, C and F a 4th, C and G a 5th, C and A a 6th, C and B a 7th, and C and C an octave. (Octaves — notes with the same name — are considered as a type of unision.)

Intervals also have different flavors — there can be major intervals, minor intervals (like C and Eb), diminished intervals (like C and Gb), augmented intervals (like C and G#), and perfect intervals (like C and F and C and G — so called because they have a perfect relationship — they are in each other’s scale).

To learn more about intervals go to http://www.playpiano.com/Articles/unisons-intervals.htm

So intervals simply measure the distance between any two notes. There are two types of intervals: consonant and dissonant. The most consonant intervals are 3rd and 6ths, while the most dissonant intervals are 2nds and 7th. 4th and 5th are somewhere inbetween — depending on the context.