1. About Chords and Keys:


A chord is simply more than one note played simultaneously. However, because the random act of doing this might not necessarily produce an attractive sound, history has passed down, and science identified, a set of combinations that work best at the simplest level.  Using three notes at a time we can go to the keyboard and, using our right hand, play any note with the thumb and place the second third fourth and fifth fingers on the successive white keys to the right. Now play the notes beneath the thumb, third and fifth finger all at the same time. That is a triad – and on this everything is based.

Now move your whole hand one white note to the right – do the same thing again. This is also a triad but now, because the hand position has changed, it will have a different sound quality, and, for convenient identification a different name. The name we give to these triads is the name of the thumb note, the ‘root’ of the triad.

So if you start with A, miss out B, play C, miss out D, play E – you have the triad of A. Move up to B on the thumb, miss out C, play D, miss out E, play F – this is a triad based on B. In other words, they are chords of A and B respectively. 

What you may have noticed is that the chords sound different based on which note is your starting point (key note). ACE for example has a darker sound than say; CEG. Now look at these chords carefully – count the physical quantity of notes from the A to the C – there is A, then a Black note (Bb), then B, and then C = 4 notes. Now do the same from C – we have C, then a black note (C#), D, another Black note (D#), then E = 5. So the structure of the keyboard is such that this combination of notes (the interval) between the Root and the ‘Third’ that form the lower part of a triad elicits a different sound at different positions on the keyboard.

Start with CEG and move up one chord at a time until you arrive at CEG an octave higher (the next time you reach the combination of CEG). Listen carefully to the ‘quality’ of each triad. CEG sounds bright and, as we have seen, that is because of the five note count between the C and the E. DFA though has a four note count – can you hear the difference – it sounds altogether darker. CEG has a major quality, DFA has a minor quality. Travelling up EGB is minor; FAC major; GBD major; ACE minor; BDF – mmm, this is the odd triad – the gap between the bottom B and the top F is one note less than that of all the other triads – so double minor or. To use the technical term a diminished triad. We can ignore this for the moment.

A very important feature of triads is that it doesn’t matter to the description or quality in which order the notes are played: so if you decide to play the C then move two notes right and play E, then three notes right to play the A (CEA): it is still an A minor chord. Try it first as ACE, now CEA: can you hear that the quality is the same. Now try EAC: same quality. All these chords are Aminor chords just different ‘inversions’ on the piano. On the guitar they are different ‘positions’ or shapes, but the principal is the same.

So what we notice is that there are three major, three minor and one diminished chord in the seven triads that make up this Triad vocabulary of the key of C. Those that share the quality of the key triad (C) in other words the major chords – are known as the Primary triads. Like Primary colours. Now count the white notes inclusively between the root notes of these primary triads:
                                C to G = five (CDEFG)     this is an interval of a Fifth
                                F to C = five (FGABC)      this is an interval of a Fifth
                                G to C = four (GABC)      this is an interval of a Fourth
                                C to F = four (CDEF)         this is an interval of a Fourth

The intervals of four and five underpin the structure of harmony throughout the history of western music. The way instruments are tuned, the scientific properties of the harmonic series, even how the piano is built, all relate to this harmonic phenomena – even the non-western blues scale derives from a 12-bar progression using chords one – four and five.


More next time!