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.

For more musical knowledge, come on over to Play Piano Catalog and browse the many courses in music.

One of the techniques you can use in your right hand to make your piano playing fuller is to add 3rds under the melody. Just make sure it is a scale note 3rd — anything else will not harmonize correctly. When 3rds don’t work at a given spot in the melody, switch to 6ths under the melody — one of those two will almost always work. For more good stuff like this, come on over to http://www.playpiano.com and sign up for our free online newsletter.

An inversion in music is a chord or interval which is “upside down.” For example, if you invert an interval of a 3rd, you get an interval of a 6th. If you invert a C chord in root position, for example, you turn it on it’s head so that C is no longer on the bottom, but now is either the middle or the top note of the chord. For more information on inversions, please go to http://www.playpiano.com/101-tips/5-inversions.htm

In addition to naming intervals by their distance apart, such as a 3rd, 6th, etc, intervals can be major, minor, perfect, augmented and diminished. Watch this short video:

An interval is the distance between any two notes, such as the distance between B and C. Intervals are named simply by the distance between the two notes, so B and C above it is called a 2nd. B and the D above it would be a 3rd, B and the E above it would be a 4th, and so on.

3rds and 6ths are called “consonant intervals”, while 2nds and 7ths are “dissonant intervals.” If you play them, you will understand why. Intervals of 4ths and 5ths are usually considered harmonic intervals too — technically they are called “perfect intervals” because each note of the interval is in each other’s scale. For example, the distance between F and C above it is a perfect 5th — notice that F is in the scale of C, and C is in the scale of F. Perfect 5ths inverted become perfect 4ths, and perfect 4ths inverted become perfect 5ths.

An interval of a 3rd inverted becomes a 6th, while a 6th inverted becomes a 3rd. Try playing these intervals on your piano, and it will become clear to you.
More about major, minor, and perfect intervals in the next post.

One note played alone is termed a“unison.” Two notes played simultaneously (or adjacent to one another) are termed an “interval.” Intervals are named by the distance between them, so there can be intervals of 2nds, 3rds, 4ths, 5^th, etc.  Chords are three or more notes (or pitch classes; strictly speaking, notes are the written form of pitches) played together. But these notes don’t necessarily have to be played simultaneously. Broken chords, or arpeggios, are three or more notes that aren’t played at the same time but closely enough to be heard as a group or whole. Sometimes in rock music the term “power chord” is used, meaning that the 3^rd is left out of a 3 note chord leaving just the root and 5^th.

Chords are most often named based on their number of notes or the type of intervals involved. Chords classified by note number are given names such as trichord (three notes), tetrachord (five notes), and hexachord (six notes). Chords classified by interval are given names such as tertian (third chords), secundal (second chords), and quartal (fourth chords). Sometimes chords are named based on both qualities. Tertian trichords, for example, are chords with three notes, each a third above each other. These type of chords are actually the most common in western music, found frequently in rock and pop.

These chords aren’t the only chords possible, however. There are several specialized chord types that seem to defy strict categorization. Inverted chords are created by turning any root position chord upside down. Seventh chords can be made by adding a fourth note to a triad — a third above the chord’s fifth — which makes the highest note a seventh from the root. Extended chords are those with notes that extend above a seventh, such as a ninth or an eleventh. But it’s important to mention that no extended chord can go above a thirteenth. By that point, the notes included will have already been played somewhere in the chord, taking it back down to an eleventh or thirteenth.

 A “slash chord” is a chord where the root of the chord is not the lowest note, which would include inversions, but also might include non-chordal notes. An example might be C/B.

 A “sus chord” – short for “suspension” – is a chord where the 3^rd of the chord is replaced by the 4^th.

The Nomenclature of Music: Unisons, Intervals, Chords from chordman on Vimeo.