Glebe Terrace

There are a number of ways to group the keys, the most usual being a combination of four principal attributes:

1. major
2. minor
3. sharps
4. flats

Major vs Minor

For every key, each octave has 7 steps (or gaps) between the notes. Each octave is split evenly into 12 semi-tones. This means that the steps are not all the same (12 ÷ 7 is not a whole number), some steps are 1 semi-tone, some are 2 semi-tones. The pattern of steps is what defines a major or minor key.

Major keys have the step pattern: 2 2 1 2 2 2 1

Minor keys have the step pattern: 2 1 2 2 1 2 2

You should now tie this back to the actual key signatures – go ahead and play this on a real (or printed out) keyboard. Understanding is helped enormously by working through this yourself for a number of different keys, both major & minor.

Every major has a relative minor. Equally, every minor has a relative major. Every relative pairing have the key signature for both major & minor keys. The relationship between the pairing is two notes which is three semi-tones. The minor key simply starts three semi-tones below the major. Now, recall that each key is named according to it’s 1^st note and you can now given any key & its key signature easily name its relative major or minor. For example: three semi-tones below C is A so C is the relative major of A (minor) and A is the relative minor of C (major); three semi-tones below A is F^#, so F^# is the relative minor of A, and A is the relative major of F^# (minor).

The next question is: if every major has a relative (natural) minor with exactly the same key signature why do we have major & minor keys at all? Why not just have one set? The answer comes down to chords and how the music is constructed. Stepping back from keys for a moment, the whole of music composition is a framework of guidelines coupled with personal and period styles. Music from Bach’s era (J.S. that is) sounds similar to other music of the period and very different from music of Beethoven’s time; within modern music, the 1980’s has a particular ‘sound’ due to similarity of style which is differnet from that of the 1960’s and the 1990’s – this is a period style. Part of this sound is due to the use of chords played within a key and in the change to a different key. Putting time-based periods aside, each composer also added their own unique approaches to the framework including use of chords, notes and changing keys. In most music it is the chords that provide the basis for baseline, melody & harmony.

Two of the principle chords used by almost every composer are 1-3-5 and 5-7-9 (which is just a way of saying 5-7-2 with the 2 in the next octave, ie above the 7). In the following example and to keep this simple we’ll stick with the simplest key signature (no sharps or flats) which is used by the keys of C major & A minor:

For C Major the chord 1-3-5 is the notes C, E, & G played all together. For its relative minor, A Minor, the chord 1-3-5 is the notes A, C, & E played all together. These have a completely different feel from each other and so a section of music built around the 1-3-5 chord of one will ‘feel’ completely different from the same approach taken in the other key. This is one fundamental reason why major & minor persist. There are others, let’s not go there.

Sharps vs Flats

I’ll update this at some point, for now “It’s left as an exercise for the reader”.