Music Theory for Beginner Bass Players: Interval Basics

October 30, 2018

Hey bass players! It’s been a few months since we talked about music theory. In my last post we explained the musical alphabet, the fretboard, and briefly introduced intervals.

In this post we’ll continue the discussion on intervals: the next step in the journey to learning music theory. Intervals pave the foundation for understanding chords, scales, and melody down the road.

Let’s get into it!

What is an interval?

Simply put, an interval is the distance between two notes. The sentiment of every scale, chord, melody and song are defined by the space between each note.

Ever wonder why a tune sounds bright and peppy while others sound dark and solemn? Check out this video of popular wedding songs, but in minor keys.

Lowering or raising even just one interval in a melody or bassline can change a song from happy to sad, or vice versa.

As mentioned in the last post, the smallest interval is a half step, aka a minor second. On the bass guitar fretboard, one half step is equal to moving up or down one fret on a given string.

1 half step = 1 fret

What defines an interval?

There are two factors that identify an interval: the distance and the value.

Let’s use a major seventh (M7) as an example – major (the value) seventh (the distance).

For distance, intervals can be primes, seconds, thirds, fourths, fifths, sixths, sevenths, and octaves. Intervals can be larger than one octave, but we’ll stick to this list for now in order to keep things simple.
Intervals can have the following values: major (raised), minor (lowered), augmented (raised), diminished (lowered), or perfect.

Seconds, thirds, sixths, and sevenths can be major or minor. It’s worth noting that they can also be augmented or diminished, but these aren’t as common. They can be augmented when a major interval is raised by an additional half step, and diminished when a minor interval is lowered by an additional half step. We usually don’t see much of these since there are often more practical, alternative ways to spell them (Remember learning about pitches having different note names in the last post? Intervals can have enharmonic equivalents as well.). For example, an augmented seventh is really the same thing as an octave, so we’d typically refer to it as an octave.

Primes, fourths, fifths, and octaves can be perfect, augmented, or diminished, but NOT major or minor.

How many intervals are there?

Again, we’ll focus on the core intervals within one octave.

A few things to mention about this section:

Although I’m using the note A as the starting note for these examples, these “shapes” can be applied just about anywhere across the fretboard.
Some intervals have more than one common fingering, which is why some of the photos below contain multiple arrows. Some intervals have even more fingerings, and not all alternate fingers are represented in these photos.

Now let’s get to it!

Minor Second (aka Half Step) = 1 half step
Major Second, (aka Whole Step) = 2 half steps
Minor Third = 3 half steps
Major Third = 4 half steps
Perfect Fourth = 5 half steps
Tritone (aka Augmented Fourth OR Diminished Fifth) = 6 half steps
Perfect Fifth = 7 half steps
Minor Sixth = 8 half steps
Major Sixth = 9 half steps
Minor Seventh = 10 half steps
Major Seventh = 11 half steps
Perfect Eighth, aka Octave = 12 half steps

It’s important to know what each interval sounds like as well. Check out this video!

How do I determine the interval between two notes?

When calculating the interval between two notes, always start with the lower note and count up to the higher note.

As mentioned earlier in the post, there are two factors that identify an interval:

1. Distance (third, fifth, seventh, etc.)

To find the distance between two notes, refer to the musical alphabet.

A B C D E F G

Let’s use the notes D and F-sharp for this example. Don’t focus on sharps and flats in this step – only the note names. Always count the first note as one, so for this example we have D (one), E (two), and F (three).

A B C D E F G

Since we landed on three, we know that this interval is some sort of third… whether it’s major or minor, we don’t know yet.

2. Value (major, minor, perfect, etc.)

To determine the value of an interval always refer to the major scale of your starting note. In our example, our starting note is D. So let’s apply the D major key signature to the musical alphabet.

A B C# D E F# G

The next step is to ask yourself, “is my top note in the bottom note’s key signature?” If the answer is yes, the interval will be either major or perfect. In this case, the answer is indeed yes! The note F-sharp is part of the D major key signature, making this an interval of a major third.

Let’s say that F-sharp was just an F-natural. In this case, our interval would be a minor third, since F-natural is part of the D minor key signature and is a half step (or “augmented prime” if you want to get technical) lower than F-sharp.

If you’re not familiar with scales and key signatures yet, here are a few alternate methods for figuring out intervals:

Count the number of half steps between the two notes (refer to the fretboard images above).
Use fretboard shapes. If you know that an octave is always two frets over and two strings up, then you can apply that to any two notes across the fretboard.

What’s the significance of intervals to me as a bassist?

Having a strong knowledge about intervals will not only help you understand chords and scales – you’ll also be able to make good musical choices when approaching your basslines. You’ll know which notes are appropriate to play, which ones you should stay away from, and which ones will add a little spice to your lines.

As a bass player it’s crucial to know how the notes you play relate to the root notes of the key signature and chords. Playing an E-flat? If you’re in the key of B-flat then you know the root is either down a perfect fourth or up a perfect fifth.

I know I’m jumping ahead a bit, but if you’re familiar with chords and how they’re structured let’s look at this chord progression: vi-V-I. Playing the first inversion of a V chord might be a good choice if the next chord in the progression is a I chord. Since the third of a V chord is also the leading tone in a scale/key, it gives the progression a great sense of movement and resolution when ascending a half step to the root of the I chord.

Well so much for a “brief overview” of intervals! Feel free to drop a comment below if you have any questions or input. As always, thanks for reading!