Who Else Wants To Learn About The Relationship Between Fourth And Fifth Intervals?

You arrived at this page because you’re interested in learning the relationship between fourth and fifth intervals.

If you’ve been around musicians for a long time, you probably must have heard the term circle of fourths and circle of fifths.

Music scholars have proven beyond every reasonable doubt that fourths and fifths are related and I’ll tell you exactly “why it is so” in this lesson.

But before we’ll go into all that, let’s discuss on perfect fourth and fifth intervals briefly.

Perfect Fourth And Perfect Fifth Intervals – Explained

An interval, according to Jermaine Griggs “is a product of the relationship between two notes, whether played together or separately.”

Two key aspects of an interval are its quality and quantity.

The quality of an interval pertains to its musical characteristics and is described using adjectives like major, minor, diminished, augmented, and perfect, while the quantity of an interval pertains to its size and is described using ordinal numbers such as first, second, third, etc.

“What Is A Perfect Fourth Interval?”

A perfect fourth interval is a product of the relationship between the first and fourth tones of the any traditional scales (like the natural major, natural minor, melodic minor, and harmonic minor.)

The first and fourth tones of the C major scale:

…are C and F (respectively):

Therefore, C and F:

…is a perfect fourth interval.

Other perfect fourth intervals include D and G:

…Eb and Ab:

…F and Bb:

…G and C:

…Ab and Db:

…B and E:

“What Is A Perfect Fifth Interval?”

The relationship between the first and the fifth tones of the natural major, natural minor, melodic minor, and harmonic minor scale produces a perfect fifth interval.

The first and fifth tones of the C major scale:

…are C and G (respectively):

Therefore, C and G:

…is a perfect fifth interval.

Other perfect fifth intervals include Db and Ab:

…Eb and Bb:

…F and C:

…G and D:

…Ab and Eb:

…B and F#:

A Short Note On Perfect Intervals

One of the properties of an interval is inversion. An interval is said to be inverted when the order of the notes changes. For example, when the interval C and A:

…is played or spelled in such a way the A comes before C:

…an inversion is produced.

In a nutshell, the inversion of C and A:

…is A and C:

The inversion of an interval changes its quantity and quality. For example, C and A:

…is a major interval, while A and C:

…is a minor interval.

“Pay Attention To This…”

The Relationship Between Fourth And Fifth Intervals

Fourth and fifth intervals are used interchangeably most of the time. For example, the music clock:

…is either described as the circle of fourths or circle of fifths.

A clear understanding of the relationship between fourth and fifth intervals will explain why they are used interchangeably.

“Let’s Proceed By Learning About The Inversion Of Intervals…”

Intervals change when they are inverted and we highlighted the change in quality in the last segment. In addition to the change in quality, there is change in quantity.

“Check Out  The Product Of The Inversion Of Certain Intervals…”

A second interval changes into a seventh interval when inverted and vice-versa

A third interval changes into a sixth interval when inverted and vice-versa

A fourth interval changes into a fifth interval when inverted and vice-versa

A fifth interval changes into a fourth interval when inverted and vice-versa

The inversion of C-F (which is a fourth interval):

…produces F-C (which is a fifth interval):

In the same vein, any given fourth interval changes into a fifth interval when inverted. The inversion of Eb-Ab (which is a fourth interval):

…produces Ab-Eb (which is a fifth interval):

The Relationship Between Fourth And Fifth Intervals

Fourth and fifth intervals are related by inversion. The inversion of a fourth interval produces a fifth interval and vice-versa.

Due to the relationship between fourths and fifths, they can be used interchangeably. The music clock:
…can either be called a circle of fourths or fifth.

Going clockwise, we have C:

…to G:

…which is a fifth. However, it’s still possible to have C:

…to G:

….which is a fourth interval.

The first interval is C to G (a fifth):

…while the second interval is G to C (a fourth):

…and an inversion of the given interval (which is C to G.)

Final Words

I’m doubly sure you’ve learned about the relationship between fourth and fifth intervals.

In  subsequent lesson we’ll apply this knowledge in the formation of chords using quartal (fourth) and quintal (fifth) harmony.

All the best!

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Chuku Onyemachi

Head of Education at HearandPlay Music Group

Onyemachi "Onye" Chuku is a Nigerian musicologist, pianist, and author. Inspired by his role model (Jermaine Griggs) who has become his mentor, what he started off as teaching musicians in his Aba-Nigeria neighborhood in April 2005 eventually morphed into an international career that has helped hundreds of thousands of musicians all around the world. Onye lives in Dubai and is currently the Head of Education at HearandPlay Music Group and the music consultant of the Gospel Music Training Center, all in California, USA.

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