Quick Note: If you haven’t checked out the Intervals Part 1 lesson in Music Theory For Bass then take a look before you try this lesson!
The last lesson focussed on perfect and major intervals, which we will be altering today to make minor, diminished and augmented. To make a major interval into a minor, we simply have to flatten it (take it down one semitone). For example, C to B is a major second, but if we flatten the B to a Bb then we have a minor second.
If we flatten a perfect interval then we make it diminished. Raising a perfect interval makes it augmented.
Let’s take a perfect fifth, C to G. If we flatten the G to a Gb, we get a diminished fifth. If we raise the G to a G# then we get an augmented fifth.
What If I Told You Fb and E# Are The Same Note?!
So you probably know that E and F are next to each other in diatonic music and don’t have a note between them (neither do B and C). In some circumstances, you may come across these notes under different names – B#, Cb, E# and Fb. Although it may sound confusing at first, B# is the enharmonic equivalent of C, meaning that they are technically the same note but are given different names depending on the circumstances. Other enharmonic equivalent notes include Cb and B, E# and F and Fb and E.
There are several reasons for the existence of these alternative note names and the most common relates to key signatures. It is more logical to put sharp accidentals in a key with sharps in the key signature as then the player doesn’t have to keep swapping between sharps and flats when they are reading. Using an enharmonic equivalent also allows you to assign one note to each degree of a scale so that you can see the scale more clearly. For example, the notes of the Cb major scale are:
Cb Db Eb Fb Gb Ab Bb
In this key, Fb – the enharmonic equivalent of E -is used to show that it is the fourth degree of the scale rather than looking like the third. Otherwise, the scale would look like this:
B Db Eb E Gb Ab Bb
This is far more confusing as there are two types of B and two types of E, but no C or F. This makes seeing the scale and relating back to the key signature much harder.
Back To Intervals…
Now we know about enharmonic equivalents, we can return to the new intervals we looked at earlier. We know that if we raise a perfect interval then we make it augmented and if we flatten it we make it diminished. Let’s take a closer look at an augmented fourth and a diminished fifth in C:
Augmented Fourth – C to F#
Diminished Fifth – C to Gb
You might have spotted that they are exactly the same and that F# is the enharmonic equivalent of Gb.
Another name for this interval is a tritone.
Major and minor intervals can also be augmented or diminished in the same way as perfect intervals – it is much less common but still useful to know. If you flatten the top note of a minor interval it becomes diminished and if you raise the top note of a major interval it becomes augmented.
Let’s take the major third pattern – C to E. If we raise the E to an E# then we have an augmented third. If we take the E down to Eb then we have a minor third. If we take the Eb down again to Ebb (E double flat), then we have a diminished third.
Here are the outcomes of any alterations you can make for reference:
Major flattened = Minor
Major raised = Augmented
Minor flattened = Diminished
Minor raised = Major
Perfect flattened = Diminished
Perfect raised = Augmented
Memorising New Intervals
To learn these new intervals, we can use the same exercise from Part One. Using the notation below for reference, take an interval and play it starting from C. Then take it up a fret and play the same shape starting on Db. Continue this all the way up to the twelfth fret before making your way back down. Do this with each interval in turn until you feel comfortable with the shape.
Hearing The Difference
Each interval has its own unique sound and it is easier to remember them at first in groups. Here are some guidelines to get you started:
Major intervals sound happy.
Minor intervals sound sad.
Diminished intervals sound scary.
Augmented intervals sound futuristic/spacey.
These are open to interpretation though and are just a rough guide to get you started.