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 TETRACHORDSby Mark Mellis

Literally, tetrachord means four strings (or four notes). In modern music theory it usually refers to a four

note segment of a scale. There are several possible variations, but for purposes of this article, I am

going to focus on two types which I will refer to as the “major tetrachord” and the “minor tetrachord.”

A major tetrachord is the rst four notes of any ascending major scale. On C that would be C-D-E-F.

Notice the pattern of whole steps and half steps. From C to D is a whole step, D-E is another whole

step, and from E-F is a half step. This pattern of W-W-H is shared by all major tetrachords.

Likewise, a minor tetrachord is the rst four notes of any ascending natural minor scale or C-D-Eb-F.

The resulting pattern for all minor tetrachords is W-H-W.

W W H W H W

One benet of knowing and learning these four note patterns is that many scales are simply a series

of two tetrachords. For example, a major scale consists of two major tetrachords separated by a whole

step. Another way of looking at this, is to play a major scale rst play the major tetrachord starting on

the root and then the major tetrachord starting on the fth.

By learning and memorizing all twelve major tetrachords, you have essentially learned all twelve major

scales. Since tetrachords contain only four notes as opposed to 7 notes in major scale (or 8 if you count

the octave), learning and memorizing tetrachords is much easier than learning and memorizing major

scales.

Major Tetrachord Minor Tetrachord

W

C Major Scale

C Major Tetrachord G Major Tetrachord

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Even scales that may seem more complex are often combinations of major and/or minor tetrachords.

For example, octatonic or diminished scales are formed by two minor tetrachords a half step apart.

Many other scales and modes contain similar combinations of tetrachords. Keep your eyes and ears

open to these patterns.

W

Other Scale/Tetrachord RelationshipsThe dorian scale, a chordscale often used to improvise over a minor seventh chord, is two minor

tetrachords a whole step apart.

D Dorian Scale

D Minor Tetrachord A Minor Tetrachord

H H

C# Diminished Scale (Half-Whole)

Eb Minor Tetrachord A Minor Tetrachord

W

C Melodic Minor Scale

C Minor Tetrachord G Major Tetrachord

HH

Eb Diminished Scale (Whole-Half)

D Minor Tetrachord Ab Minor Tetrachord (enharmonic)