Intervals in Western Music Theory Explained
Intervals are really the building blocks of music. In my mind, I often relate them to looking at music theory through a microscope. It's imperative to understand them and even better to be able to recognize them by ear.
An interval is simply the tonal gap between two notes. The smallest possible interval in Western music is a half step, otherwise know as a 'minor second' (we'll get there in a bit). Take a look at the keyboard on a piano; if you were to play C and then play the next immediate note up, C#, that interval is called a half step. Can you guess what constitutes a whole step? If you said (or thought) two half steps then you're right! So, playing C to D would be a whole step because you are skipping two half steps along the way. It's a pretty simple concept and a huge building block for scales and chords.
OK, remember how I just touched on the term 'minor second' for the half step explanation above? When talking about musical intervals, this is the nomenclature we use.
|Minor Second||1 half step|
|Major Second||2 half steps|
|Minor Third||3 half steps|
|Major Third||4 half steps|
|Perfect Fourth||5 half steps|
|Augmented Fourth||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|
|Octave||12 half steps|
There are two levels of memorization need to really get these puppies nailed in your head. The first is to just memorize the the names at face value, exactly how the chart above illustrates. The second is to put them into the context of a scale. For example, let's figure out what a major third above C is by using the C major scale.
C Major Scale
C D E F G A B
A rule to always keep in mind is this: all notes in a major scale are major or perfect intervals from the root note. Since we know that the third note of the C major scale is a major third from C we can say without a doubt that E is a major third above C. This way of learning intervals is the best because not only are you learning intervals, but you're also learning about scales. Don't forget to check out the lessons on major and minor scales when you're done reading this lesson.
Let's do another one, how about a minor sixth above G.
G Major Scale
G A B C D E F#
You can count 8 half steps if you want, but if you need to know fast that isn't going to get you there in time. If we use the major scale based off of G we can take the sixth note, which we know is a major sixth above G, and bring it down a half step to transform it into a minor sixth.