Intervals: Unisons and Octaves

In the previous installment I made the case for the importance of learning your intervals. Assuming you bought my argument, it’s time to jump in and learn some!

Intervals often come in pairs, especially when we get into inversions (a topic we’ll cover next time). But as a starting point, let’s tackle the two most obvious kinds of intervals: the unison and the octave.

The unison interval is simply two notes playing the exact same pitch. The distance is zero steps. On the guitar these are a little challenging to play unless you use open strings or you move up the neck where the frets are closer together. Here’s one way to play a unison:

Open-string unison

Open-string unison

If you ever tune your guitar with itself you’re already using unison intervals.

An octave is an interval in which one of the notes is some factor higher or lower in terms of frequency. Western music describes music only in terms of twelve notes. To cover all of the possible pitches we repeat the note names. When musicians talk about an A or C note, they’re not necessarily being specific about the exact pitch. In scientific terms, an open A string (in standard tuning) is around 440Hz. Play the 12th fret of that same string and the frequency doubles to around 880Hz (for obscure mathematical reasons things don’t turn out to be perfect frequency numbers).

Octaves turn out to be pretty useful musically on the guitar. For one, they sound good played together. Put your amp on a clean setting, switch to the neck pickup and play something like this:

Octaves à la Wes Montgomery

Octaves à la Wes Montgomery

Voìla! Instant jazz! That jazzy sound you’re hearing was invented by Wes Montgomery who used octaves a lot to thicken up his lead lines. (Note: if you really want to get that Wes Montgomery sound, stroke the notes with your thumb instead of a pick.)

Octaves also work well on a high-gain setting too. Assuming you’re guitar is in tune, the frequencies of the notes in octaves work well together even with lots of distortion. Make sure that you deaden the string between the fretted notes with the inside of your first finger. That way you can hit all three strings with a single pick-stroke, but keep the middle string from making any sound. Here are some octaves in a rock context from Van Halen’s Black and Blue:

Octaves in action: Van Halen’s “Black And Blue”

Octaves in action: Van Halen’s “Black And Blue”

On the guitar octaves are extremely helpful in visually dividing up the fretboard. If you know the relations of the notes in a chord, arpeggio or scale within one octave, it’s pretty easy to visualize it in another. For example, if you want to improvise using a certain scale, it helps to know the scale in octave-sized “chunks” rather than trying to remember the entire thing all the way up and down the neck.

Let’s look at the unison shapes. These can be quite a stretch! Don’t worry about trying to play these as much as try to remember what these unison shapes look like on the fretboard.

Close String Unisons

Close String Unisons

Notice that, because of the way the guitar is tuned, the shape between the 2nd and 3rd strings is different from the others. We’ll run into that difference over and over again in our study of intervals.

Now let’s look at the shapes for octaves. There are two basic octave shapes: on pairs of strings two strings apart and pairs of string three strings apart. Here are the shapes for the first type:

Octave shapes (skipped strings)

Octave shapes (skipped strings)

And here are the shapes for the second type:

Octave shapes (two skipped strings)

Octave shapes (two skipped strings)

When I play any sort of melodies with octaves I usually stick to the first shape since it’s less strings I have to quiet down. But I still know what the octave shapes of the other type look like and I use them a lot in improvising.

A good thing to play around with is figuring out how to play melodies in octaves. You could pick any melody, “Happy Birthday”, the theme from Jeopardy, a Beatles song, whatever. Just figure out how to play the melody with octaves. It can be kind of a brain-bender at first, but it’s a great way to get some experience with octave shapes and moving them around the fretboard. One thing about octave melodies is that you tend to move up and down the neck a lot more.

A big part of learning the intervals is matching how they sound with how they look on the fretboard. With enough exposure, you’ll automatically associate particular fretboard shapes with certain sounds. This becomes incredibly powerful when you improvise because your musical mind will know what it wants to hear and your fingers will just know what to do.

In the next installment we’ll cover the two most common intervals in hard-rock: fourths and fifths. We’ll also see how they relate to each other with the fancy name of intervals.

Until next time, keep rocking!