Once you are able to convert a given chord symbol into a group of notes, you should then turn your attention to learning how to convert a set of notes...into a chord symbol! Again, chord spellings are the key. The following text outlines the approach you should take:
First, let's be clear that any group of notes played together as a chord, has more than one possible name. Hence the reason we have what are called 'chord synonyms'. To reduce the number of possible chord names given to a group of notes, let us make one assumption (for now at least):
that one of the notes in said group is the root from which the chord will take its name.
Of course, in practical terms, there are many instances where the root is not played (by a given chord player -keys or guitar for example) and is perhaps left to a bass player. This is common in Jazz with its preference for complex chords (both in name and sound). But we will ignore these cases for now; as it will just add to the confusion and possibilities for chord names.
So...which note in a group of notes is the root note? Remember, a root note is the one that gives the chord its foundation (and also its letter name). But you must not assume that the root is the lowest pitched note (that's if we even know the pitch order of said notes, for they may just be presented to us as arabic letters written down). You may be ware of the distinction between root position chords - where the root is indeed the lowest note - and inversions - where it is not. When we first begin to work out a chord name for a group of notes, we may not know whether we have a root position chord or an inversion on our hands. Keep an open mind! Having said that, there are sometimes clues straight away as to what the root note is: sometimes the root occurs more than once in said group; or if the chord is notated on a stave or indeed played on a chordal instrument, the root may present itself as obvious.
But still, we need to be sure.
I will say two things at this point, that should guide us:
* chords do not normally exist in isolation from one another; their natural context is the chord progression, which are themselves usually determined by musical keys. Therefore, with a bit of knowledge of diatonic chord formulas, it should be possible to choose a root that produces a name that fits with the other chords it is surrounded by; and your perception of the key that exists.
* choose a root that produces the simplest name: in a four note chord, for example, any of the notes could - in theory - be the root, and each giving rise to a chord name of sorts. But one should stand out as producing the simplest name. The chances are that that note is indeed the root.
Another tip: look for triads within groups of notes; because triads usually exist as the core of all larger chords. That's why I say one ought to learn the notes in all triads - instant access just like the multiplication times tables! There are four triad types with 12 possible roots; therefore 48 triads you should know straight away. Look out for them in all groups of notes.
another clue: look for alternate letters in a group of notes; thus pointing to the most likely root note (the starting note). Assuming tertian harmony (chords based on 3rd's), the letters should indeed be alternate. If they are not, then perhaps you have chosen the wrong root note.
So, let's take a look at an example:
Question: Work out a chord name for the following group of notes: G C E A.
step 1. see if you can spot any of the 48 triads; or just look for alternate letters from a given note
I can see A C E as an A minor chord
I can see C E G as a C major chord
The note A produces a series of alternate letters: A C E G.
The note C does not produce a series of alternate letters: C E G A. A is not an alternate letter!!!
Therefore, it is looking likely that the root of this chord is A.
Assuming that to be the case, what is the name of chord?
Step 2. Refer to the Key of A Major: A B C# D E F# G# A
Then place the chord names against the scale to work out its spelling:
A B C# D E F# G# A
A C E G
1 b3 5 b7
This spelling indicates a Minor 7th (m7) type of chord.
Hence, the chord is A minor 7th or Am7
Exercise: work out chord names to the following groups of notes:
* F# D C A
* D G F# B
* D B G E
* E F C A
* G# A E C#
* B F# A D
* Eb C G Bb
* G# B D E
* D F B A
* D# A F# C
clue: all the chords above are 7th's of one description or another!