Tetrachords

What is a tetrachord?

A tetrachord is a group of four consecutive notes. The prefix “tetra” means four, and chord comes from the Greek word “chordon,” which means string, referring to a string on a musical instrument like a lyre. Tetrachords are the building blocks of musical scales. A one-octave piano scale is made up of two tetrachords that sit directly next to each other on the keyboard.

What are common tetrachord formulas?

Basic tetrachords are made up of two whole steps and a single half step. The position of the half step determines what kind of tetrachord it is.

Major: whole - whole - half

Minor: whole - half - whole

Upper Minor: half - whole - whole (this one is also called the Phrygian tetrachord).

Using these tetrachords, you can build the major and natural minor scales. To build a harmonic minor scale, add another tetrachord, the harmonic tetrachord. In this tetrachord, there is a pair of notes that is separated by one and a half steps.

Harmonic: half - whole+half - half

How do you build scales with tetrachords?

A major scale consists of two major tetrachords joined by a whole step. This is the pattern:

[ whole - whole - half ] - whole - [ whole - whole - half ]

A natural minor scale consists of a minor tetrachord, a whole step, and then an upper minor tetrachord.

[ whole - half - whole ] - whole - [ half - whole - whole ]

A harmonic minor scale consists of a minor tetrachord, a whole step, and then a harmonic tetrachord.

[ whole - half - whole ] - whole - [ half - whole+half - half ]

A melodic minor scale consists of a minor tetrachord, a whole step, and a major tetrachord.

[ whole - half - whole ] - whole - [ whole - whole - half ]

Once you understand tetrachords and the way they form scales, transposing music from one key to another becomes easier to understand.

What is an example of a tetrachord?

A simple example is the minor tetrachord that makes up the first four notes of the A minor scale. It consists of the notes A - B - C - D. The upper four notes of the A minor scale create an upper minor tetrachord, with the notes E - F - G - A.

How many tetrachords are there?

The number of possible tetrachords depends on the rules of music theory that you’re using. In traditional diatonic music, there are only three main tetrachords, major, minor, and harmonic. If you are considering all the possible ways that four notes can be played consecutively in the 12-tone chromatic scale, then there are 29 possible tetrachords. 

What are tetrachords used for in music?

Tetrachords are the building blocks of musical scales. Four-note patterns are easier to understand and remember than larger groups of notes, so if you understand tetrachords and how to put them together, it’s easier to understand all kinds of musical scales.

What is the origin of the tetrachord?

Tetrachords originated in ancient Greek music theory. In ancient Greece, tetrachords were considered to be complete musical units, and one-octave scales were thought of as being built from two tetrachords. The top and bottom notes of a tetrachord were always the interval of a fourth apart, and the two notes in between could be tuned to various different intervals.

Hello and welcome back. I'm Joseph Hoffman.
Today we're going into new music theory territory by learning a new kind of scale called the tetrachord.
What is a tetrachord?
Well Tetra is a Greek prefix that means four like the number four.
So a tetrachord is a family of four notes all one step apart.
By the end of today we're going to learn how to combine two tetrachords to build a full eight note or one octave scale.
Let's come to the piano to check it out.
Here I have drawn the C major tetrachord.
You'll notice it's just one key different from the C major pentascale,
which we're very familiar with.
Tetra means four, so we just go up these four notes. DO RE MI FA
Putting the half step here at the top of the tetrachord.
Now, in music very often we want to go a full octave.
Remember, oct means eight,
and to go an octave that's going to be eight notes. Four plus four more.
So if you put two tetrachords together,
like this, you can get a full octave scale.
So down here we have C D E F, and then up here we have G A B C.
Now let's notice some things about these tetrachords.
You'll notice that the top two notes of this tetrachord form the half step.
Same thing with this tetrachord.
Two notes at the top make the half step.
You put two tetrachords together like that, and that builds a one octave major scale.
So this is cool because it will open up so many new songs that we can perform when we can go the full octave.
Now in solfège, let's give a name to each of these notes of the octave scale.
we ha ...