Want to learn something on the guitar that is theoretically heavy but also extremely practical and easy to apply?
You may have not heard the term "tetrachord" before, but it's worth your while for one basic reason:
It's a useful melodic building block.
So how does it benefit you?
Knowing what a tetrachord is gives you structure for building lead patterns, solos, and other single-note sequences that sit over top of a bass line or underlying chord progression. If you know what it is, it can help you instantly become a better improviser and a more melodic lead player, as long as you're playing in a major key (more on that later).
But what is it?
The Definition
The traditional definition of a tetrachord is a four-note sequence that spans the interval of a perfect fourth.
In modern music theory, it can refer to any four-note segment.
For our purposes, we're sticking with the more formal definition; a segment of a major scale where that scale can be defined as two tetrachords separated by a whole step.
So our tetrachord would follow this interval pattern:
Whole | Whole | Half
or...
Half | Whole | Whole
Here are a few tabbed examples:
E|-----------------
B|-----------------
G|--2--3--5--7--
D|-----------------
A|-----------------
E|-----------------
E|-----------------
B|-------------3--
G|--2--3--5------
D|-----------------
A|-----------------
E|-----------------
E|-----------------
B|-----------------
G|-----------------
D|--4--5--7--9--
A|-----------------
E|-----------------
E|-----------------
B|-----------------
G|-----------4----
D|--4--5--7------
A|-----------------
E|-----------------
You can either play the entire sequence on one string or break it up between two.
Seeing it on one line is a good place to start as it helps you visualize the movement a little more clearly. However, be sure that you can identify the sequence between two strings as well.
Exercises
We can get familiar with the tetrachord pattern using exercises that will anchor the movement in our minds and help with muscle memory.
It shouldn't take long before the movements become instinctual.
You'll need some strength in your pinky finger, but that's something these exercises should help with if you're having problems in that area.
Let's start with some technique for our original pattern.
E|-----------------
B|-----------------
G|--2--3--5--7--
D|-----------------
A|-----------------
E|-----------------
How could we move through this shape more efficiently?
Technique
I see two opportunities to apply good technique and optimize this pattern. First, the move from the second to third fret could be handled by using a hammer-on. In other words, we don't really have to pick the note at the third fret.
Secondly, the note at the seventh fret could be played by sliding up from the fifth.
So that means we'll pick only two notes: the one on the second and fifth frets (A and C if you want to get technical).
Our tab then becomes:
E|-----------------
B|-----------------
G|--2h3--5/--7--
D|-----------------
A|-----------------
E|-----------------
A good exercise to start with is to run through this pattern on the fourth and third strings.
Exercise #1
E|-----------------------------
B|-----------------------------
G|--------------2h3--5/--7--
D|--2h3--5/--7--------------
A|-----------------------------
E|-----------------------------
Run through this several times until it feels comfortable.
Now we can run the same pattern, but use our string-to-string form instead so that the movement is more efficient.
Exercise #2
E|-------------------------
B|----------------------3--
G|------------2h3--5----
D|--2h3--5--------------
A|-------------------------
E|-------------------------
E|-------------------------
B|--3---------------------
G|-----5--3p2-----------
D|---------------5--3p2--
A|-------------------------
E|-------------------------
As you move back down the pattern, the jump from the third to the second fret can be handled with a pull-off.
Let's take this a step further by turning our tetrachord into a full major scale.
Per Wikipedia, a major scale can be thought of as two identical tetrachords separated by a whole step. Our resulting tab would look like this:
E|-------------------------------------
B|-------------------------------------
G|-------------------------------------
D|--3--5--7--8--10--12--14--15--
A|-------------------------------------
E|-------------------------------------
On its own, I wouldn't call this challenging. But if we spread the notes out over a couple more strings, we can get a scale shape that can serve as a helpful exercise.
Exercise #3
E|------------------------------
B|-------------------3--5--6--
G|---------2--3--5------------
D|--3--5-----------------------
A|-----------------------------
E|------------------------------
It's a simple movement, but certainly worth memorizing to serve as a reference point for improvisation and even for learning other scales.
Let's take the shape we get from the fourth and third strings (D and G) and use it to create our fourth exercise.
Exercise #4
E|-------------------------------------
B|-------------------------------------
G|--------------------------2--3--5--
D|-------------------3--5-------------
A|---------2--3--5--------------------
E|--3--5------------------------------
E|--------------------------------------------------
B|--------------------------------------------------
G|------------------------------------9--10--12--
D|--------------------------10--12----------------
A|-------------9--10--12-------------------------
E|--10--12----------------------------------------
The tab is easily transposed so I went ahead and moved it to the third and 10th fret on the sixth string for a different feel. Though you can start at whatever fret or string you choose.
Application
So what exactly do we do with this small bit of information?
After all, it's only four notes.
One of the ways this concept is useful is that it helps provide a layer of structure to our playing and gives us a way to make sense of intervals as we get acquainted with the fretboard.
Whenever I teach intervals, the tetrachord and basic major scale are the next two topics I cover.
That way as complexity increases we're progressively building a foundation on which we can understand the fretboard. For example; you might learn how to play a single note, then intervals, tetrachords and the major scale.
The next step would be to look at triadic arpeggios and chords, then delve into basic open chords.
What I see is that a lot of people skip from single notes to open chords and rarely learn (or are taught) the step-by-step details in between. So when it comes to application, tetrachords are a part of the learning process that can be applied in a limitless number of situations.
Incremental learning is what really makes it useful.
As far as applying it in the real world, here's where it can really help you:
Scales
Tetrachords are a fantastic prerequisite for learning scales. They strengthen your pinky finger and get you used to playing the kind of patterns and intervals that you'll frequently encounter when you start learning basic scales like pentatonic and blues formations.
Improvisation in Major Key
I've found that when improvising in a major key the tetrachord sequence is almost always useful for finding notes that resolve with a chord. So if you know that interval sequence (whole, whole and half) you can string together groups of notes and come up with something more interesting and dynamic.
Intervals
Though I do teach intervals before tetrachords, I believe that playing and being able to identify tetrachords can provide a valuable "look back" and review of intervals that help tie them into what you learn in the future. It's a building block that gets you from intervals to scales, thereby helping you to better understand the purpose of both.
Your Thoughts
What's your take on the incremental learning process of the guitar? Do you find the topic of tetrachords to be practical and useful?
Share your thoughts with us in the comments section below.
Bobby Kittleberger is the founder and editor of Guitar Chalk and Guitar Bargain. You can get in touch with him here or via Facebook, Twitter and Google Plus.
Flickr Commons Image Courtesy of vipa
