Lesson 2 (A Useful Interval)
| Deep calls to deep at the sound of Thy waterfalls (Psalm 42:7) |
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The Bottom Line: An interval is a musical term meaning the distance between two notes.
Bass-ics
Western music uses a repeating sequence of twelve notes, each one semitone away from its neighbours (one semitone = one fret):
| ... 1 2 3 4 5 6 7 8 9 10 11 12 ... ... C C# D D# E F F# G G# A A# B ... |
(C# = Db; sharp (#) means one semitone higher, flat (b) means one semitone lower)
To create a major scale, we take seven of these notes in a fixed pattern of tone - tone - semitone - tone - tone - tone (one tone = two semitones, ie two frets). For example, C major is C D E F G A B, while G major is G A B C D E F#. Other types of scales use different patterns but share the fact that they repeat across the twelve separate notes.
Each note in a major scale is given a number from 1 to 7.
| 1 2 3 4 5 6 7 C D E F G A B G A B C D E F# |
This gives an easy way of changing from one key to another (if a song is said to be in the key of x, it is based around the notes of the scale x). If you are playing a 3 chord trick in C major, using C, F and G, it becomes G, C and D in the key of G major.
Back on Track
The interval betwen C and E is two tones (four semitones) and is known as a major third - the gap between the first and third notes of a major scale). If you play C and E at the same time, or near each other, you suggest the sound of a C major chord.
A C major chord also needs a G. This is seven semitones above C and is known as a perfect fifth. However, it is also three semitones above E, an interval known as a minor third. A minor third stacked on top of a major third sounds like a major chord based on the note at the bottom.
What do you get if you stack a major third on top of a minor third (eg. C Eb G)? The answer is C minor. The interval between the C and G is still a perfect fifth, but the order of the thirds has been changed. Thirds (major and minor) provide the flavour of a chord. If a fifth is like pasta, a third is the sauce...
Room at the Top
There is room for one more third at the top, which will hit either the seventh or flattened seventh of the scale. The most common combinations are C major + major third (C E G B) = Cmaj7; C major + minor third (C E G Bb) = C7; C minor + minor third (C Eb G Bb) = Cm7.
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