What is a tetrachord?

A tetrachord is a combination of four specific tones. “Tetra” means four and “chord” in this case just means: “a collection of tones”.

It’s not a chord in the sense that you use it to harmonize a melody. Blame the old Greeks for the terminology. :)

The interval formula for a tetrachord is: W W H

This means the first three tones are each a whole-step apart (W), but the distance to the last tone is only a half-step (H).

(Remember that a half-step is simply two notes next to each other, while a whole-step skips a key.)

Tetrachord formula

Why would you want to know about a tetrachord? Well, you don’t really… but it’s fun anyway. :-)

Here’s a trick: By stacking two tetrachords on top of each other, you create a major scale.

So if we begin at C and build a tetrachord, the tones are: C D E F

Then we skip a whole-step and build a second tetrachord starting on G: G A B C

Verify it for yourself: G to A is a whole-step, A to B is the second whole-step, and B to C is the final half-step.

Two tetrachords make up the C major scale

That means a tetrachord is exactly half of a major scale. Which half? It doesn’t matter!

Here’s the fun part: if we build another tetrachord on top of this we get: D E F# G

Did you realize that we have just created the major scale of G?

The G major scale with tetrachords

If we build another tetrachord on top, we get the D major scale:

The D major scale with tetrachords

And so on… You can go clockwise around the Circle of Fifths this way until you get back to where you started.

Read more articles on Piano Clues:

Basic Theory


Chords and Harmony


The Circle of Fifths


Arrangement, Improvisation and Composition


Reading Music and Sheet Music


How to Record Piano


Software and Virtual Instruments


Scales and Exercises


Digital Pianos


Links and Other Stuff


Comments

  1. Shanna says:

    this was a lot of help!

  2. Selina says:

    Thanks this information was really useful ! (:

  3. lucy says:

    thanks so much it helped me alot!!!

  4. simon keys says:

    Your teaching has made know a lot about my playing of the piano.keep up the good works.
    Cheers

  5. Isabella says:

    THIS IS SOOOOOOOO AWESOME AND USEFUL!!! THANKS A LOT!!! :D

  6. Lica says:

    I am so elated to find such information . I am so grateful and I do believe this is such a selfless gesture. Thank you so much, I don’t mind leaving a tip but I have a problem displaying my credit card if there is another way please let me know.

  7. salma abdulai says:

    this helped me alot

  8. Melody Smith says:

    This helped me tonnes :)

  9. Paul says:

    OMG
    im going to write a 10/10 in my music test thanx so much!

  10. benjamin says:

    pls can u teach me chord substitution

  11. olasunkanmi says:

    Figure out how to relate a tetrachord of a scale on different keys to other keys to still result in the same key at the end of a calculation.

  12. Nicole says:

    This is such a good explaination. Thank you. Do you have DVDs for sale?

Reverse Chord Finder

Reverse Chord Finder Pro for iPhone

This app lets you find out which chords you are playing. You select the notes on a piano keyboard and Reverse Chord Finder tells you the names of the matching chords. The ideal app for songwriters, musicians and music students. Get it from the iPhone App Store »

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