Introduction to Intervals

Why Do I Care?

When we first learn to play the guitar, most of what we play is repeating something we’ve learned either by reading notation or tab, or having someone show us the lick. We’re so focused on conquering the mechanics of playing that we don’t really know what we’re playing. As you progress you want to know a little more about what you’re playing. You might ask questions like, why do these notes go together?

The knowledge of what you play and what you hear can be described by music theory. Oooh, theory—big word, right? Now don’t get into a panic. This isn’t the same as “particle physics theory”. You won’t have to spend years in labs or working out mathematical equations. Learning a little won’t kill you and, despite what some people think, it won’t make you any less musical.

Relationships

Nearly all music we find engaging involves more than one pitch. The relations between those pitches turn out to be pretty important so they’re worth some study. A relationship between two musical pitches is called an interval and they are a great place to start to learn more about both music in general, and how it applies to the guitar. Intervals are used to describe melody as well as harmony. Intervals describe the scales, arpeggios and chords we all use, whether we know what they’re called or not.

Once you grasp the basic idea of intervals, how they sound and how they look on the fretboard, you can expand that knowledge to full scales, chords and arpeggios. But you can’t describe those things until you know what intervals you’re talking about in the first place. So let’s jump in and learn what these are all about.

There are two ways we can describe a relationship between pitches. The most basic one simply counts the number of chromatic notes between pitches. On a guitar, each chromatic note is the same as one fret. Somewhat confusingly, the one-fret distance is called a half-tone, semi-tone or half-step. A two-fret distance is called a whole-tone, whole-step or full-step.

Put a finger on the 3rd fret of the 6th string. Now put a finger on the 5th fret of the same string. That distance is a whole-step. Now move your finger from the 5th fret to the 4th fret. That distance is a half-step. In Western music, the half-step is the smallest distance we have between pitches. Other cultures may have more or less fine-grained intervals between pitches. Musical systems with smaller distances are called micro-tonal from the standpoint of Western music.

We can describe scales, chords and arpeggios in terms of tones or steps, but it gets a little unwieldy at a certain point. Describing a five- or six-note chord by naming the distance between each note this way is pretty inefficient. So musicians invented another way to refer to intervals.

Western music uses letters and some funny symbols to name notes. We only have twelve notes in Western music. If you look at a piano or a guitar, it’s pretty obvious that there are more than twelve pitches, so note names are repeated—they go in a cycle.

We use the letters A through G, but you’ll notice that that’s only seven notes. Where are the other five notes? Those are described as accidentals and require us to put a funny symbol (either a ♯ or ♭) after the letter name. Confusingly, accidentals can often have two different names, depending on the key you’re in. What’s important to learn here is the order of the note names and that they repeat in a cycle.

The note names are:

A - A♯ or B♭ -  B - C -  C♯ or D♭ -  D - D♯ or E♭ -  E - F -  F♯ or G♭ - G -  G♯ or A♭

The ♯ symbol is called a “sharp” and is meant to be a half-step (one-fret) higher than the letter note. The ♭ symbol is called a “flat” is a half-step (one fret) lower than the letter note. Not every note has a sharp or flat version. Weird, huh? This is just one of those things you need to memorize, like your times tables, so that you can move on to bigger and better things.

The Major Scale

The other way we refer to intervals requires an understanding of the major scale first. This other naming system is better at communicating more information quickly than the other, but it relies on describing intervals relative to the major scale. 

So what is the major scale? Well, that we can describe in terms of steps or tones.

A major scale

A major scale

It doesn’t matter which note we start on. In the key of A, the next note is up a whole-step which is B. The next degree is up another whole-step (two frets) and that’s C♯. The next interval is a half-step (one fret) up which is D. The next is a whole-step up (two frets) which is E. The sixth degree is up another whole-step (two more frets) which is F♯. The seventh degree is a whole-step up (two frets) which is G♯. Finally, the last interval is a half-step up (one fret) which lands us back on A, but up one octave.

Why does this matter? Because the naming system we use is based on the intervals from the major scale. When someone says “a third”, we know that they mean a distance two whole-steps, because the third degree in the major scale is two whole-steps. It doesn’t matter what note we’re talking about, the relative distance is the same.

Okay, this is enough to chew on for now. In the next post we’ll look at two of the simplest intervals: the unison and the octave.

Until next time, keep rocking!