The Concept Of Key

Essentially a key is a scale and a scale is a key. If you are playing in a key, in its most strict sense, you would be playing a series of chords taken from the diatonic harmony of that key. Also, a melody containing only notes from the major scale will be played at the same time as that chord progression. In its most strict sense, that is playing in key.

A key is normally established by sounding the one (I) chord, also called the tonic. In each of the examples below the C major chord has been played to establish the key. Since music is basically a process of establishing a key and returning to the one (I) chord of that key through a variety of chord changes, the most common chord changes are a matter of basic knowledge.

All songs, in every style revolve around pleasing combinations of chords called cadences. The cadence is of feeling of release and rest that is produced by arriving at a particular chord. In any key, the I, IV and the V are what I call the 3 primary chords as they are the source material for countless popular songs.

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The two cadences studied below, the I – IV and I – V cadences or the plagal cadence and the authentic cadence respectively, are essential and indispensible tools for any musician, writer or arranger. The cadence is the basic building block of all popular, rock, blues and jazz songwriting and none are more important and useful than those of the I – IV and I – V varieties. When you hear or feel that sense of homecoming, of rest and resolution, it means that a cadence has been produced.

Of course, always keep the basic diatonic chords in the key of the moment at the forefront of your thinking. The table below represents what your initial thinking should be when you encounter music in the key of C. Think of music theory as a cool, complex game and the major scale as the playing field for that game. The playing pieces are the chords and the roman numeral names given to them.

I
II
III
IV
V
VI
VII
I
C Major
D minor
E minor
F Major
G Major
A minor
B diminished
C Major
Do
Re
Mi
Fa
Sol
La
Ti
Do

Cadences

The I to V cadence is the strongest cadence in music and is called the authentic cadence. In the key of C, G major is the five chord, the dominant chord. To me it means that it dominates the key demanding a return to home base, the one chord, the tonic.

Knowing the sound of the basic cadences is usually achieved with playing and listening to exercises like the one below in a repetitive manner. That being said, I also like to associate the cadences with common knowledge or traditional songs so thie information has a little life and artistic meaning to it. The I to V cadence appears in traditional country songs to give the listener that strong sense of chord to chord motion.

The I to IV cadence is more of a gut bucket cadence called the Plagal Cadence or the Amen Cadence. To me it sounds emotional or evocative. The four chord, F major in this case, is also called the Sub Dominant Chord. It does not have to return to C and is classically thought of a precursor to the dominant chord.

The subdominant chord (F major in this case), or the IV chord, also has a little of its own stability which means it can be a point of rest or a point of departure to another chord other than C or G. The IV chord can also be the basis of its own stable section, such as the bridge of a rock song.

It is fun and interesting to use music theory and analyze famous and favorite songs. It is importanbt to note that although I to V can ‘sound country’ and the the I to IV change ‘rocks hard’ the theoretical concept of the cadence or certain cadences do not belong to any style, any cadence can be found in any style.

The Concept Of Key

If a key is a scale and a scale is a key, then you are playing in that key if you are using a few simple cadences based on diatonic chords and a melodic passage made up of notes entirely in the scale. It’s that simple.

This is not to trivialize the power of diatonic cadences and diatonic melodies, many great compositions have been based on surprisingly simplistic ideas. Below is a simple arrangement of The Blue Danube Waltz by Johann Strauss, a master composer and is chosen because most of us know it very, very well. The example contains both a harmonic and melodic analysis of the song as well as a small ban himd arrangement for listening.

Here, I chord, IV chord and V chord are doing their normal jobs quite beautifully.

  • One Chord- or Tonic Chord, creating a feeling of rest, stability and coming home.
  • Five Chord- or Doninant Chord, creating tension and a desire to return to the tonic.
  • Four Chord- or Sub Dominant Chord, performin its common function of preceding the V chord.

As you listen to the example, notice the relative, and stable nature of the one chord, “C” or tonic. The five chord, “G” or the dominant chord is also doing its job perfectly of drawing your ear back to home base. The four chord, or sub dominant is traditionally thought of as a chord to proceed the dominant chord. so the subdominant chorddoes have a little bit of strength and stability of its own.

This song sums up the concept of key perfectly. Not to over simplify, there is still a tremendous amount of study to be done concerning the I. IV and V chords, but a strong melody comprised of only major scale tones and strong cadences consisting of chords in the key provide your year with a stable environment, that environment is called the key. The song above is in the key of C major because every note in the melody and every note in every chord are taken from C major scale. (although this song does contain an F sharp note at the end of the melody, it is merely a chromatic scale passing note, and does not affect the overall sound, or sensation of key of the song)

Transposing

Transposing means changing key. Everything we have done so far has been in the key of C, meaning we are using a C major scale. The first note of that scale is of course C. If we were to play a major scale ( Do – Re – Mi – Fa – Sol – La – Ti – Do) beginning on another note, let’s say G for example, we would then be playing a scale in the key of G. in the illustration below you can see what a G major scale looks like when it is played on a keyboard. In order to preserve the formula, the order of half steps and whole steps, it was necessary to use one black key. The name of that note is F sharp, it is absolutely necessary to have that F sharp included if you’re going to play a G major scale. The formula demands the F sharp note, because that note, the seventh note of the scale, must be one halfstep lower than the G note. With that F sharp note in place the formula is now correct.Therefore it is said the key of G has one sharp.

Transposing

Transposing means changing key. Everything we have done so far has been in the key of C, meaning we are using a C major scale. The first note of that scale is of course C. If we were to play a major scale ( Do – Re – Mi – Fa – Sol – La – Ti – Do) beginning on another note, let’s say G for example, we would then be playing a scale in the key of G. in the illustration below you can see what a G major scale looks like when it is played on a keyboard. In order to preserve the formula, the order of half steps and whole steps, it was necessary to use one black key. The name of that note is F sharp, it is absolutely necessary to have that F sharp included if you’re going to play a G major scale. The formula demands the F sharp note, because that note, the seventh note of the scale, must be one halfstep lower than the G note. With that F sharp note in place the formula is now correct.Therefore it is said the key of G has one sharp.

In this lesson, we started by reviewing a C major scale and transposed that scale to G major. For the remainder of this lesson we will work in the key of G major. below is a table comparing the two keys. notice they are sharing a formula, all major scales have the same formula, but the spellings of the scale are unique. There is only one key with no sharps or flats, that is the key of C. There is only one key, only one major scale, with one sharp -and that is the key of G Major

Formula for both keys
1
2
3
4
5
6
7
1

G Major Spelling

G
A
B
C
D
E
F#
G
C Major Spelling
C
D
E
F
G
A
B
C
Solfege for both keys
Do
Re
Mi
Fa
Sol
La
Ti
Do

Apart from spelling, all things that were true in the key of C are true in the key of G.this is true for harmonies of the major scale, that means the same chords appear in the same order in both keys. In any major key, major scale, the one chord is a major the two chord is a minor the three chord is a minor and so on. As you learn the two keys of C and G, study the table below illustrating the harmonies of the major scale.

Harmony
I
II
III
IV
V
VI
VII
I
G Major Harmony
G Major
A minor
B minor
C Major
D Major
E minor
F# diminished
G Major
C Major Harmony

C Major
D minor
E minor
F Major
G Major
A minor
B diminished
C Major

Names for both keys.

tonic
supertonic
mediant
sub dominant
dominant
sub tonic
leading
tonic

The musical example below is another version of the Blue Danube waltz, this one has been transposed to G. The lines and spaces on which the melody appears are different. The names of the chords and melodic pitches are different. The harmonic analysis however remains the same as does the melodic analysis. This is because the formula for any major scale, and the harmony for any major scale are exactly the same in every regard except for spelling. That is the actual letter names of the notes.

The illustration below is meant to explain the principle of the key signature. The key signature represents a major scale. In the case of the key signature for C major below it is representing the C major scale because there are no sharps or flats appearing in the key signature. This is because to please C major scale on the keyboard you use only the white keys no sharps or flats. The key signature for G major appearing to the right of C major does have one sharp. That sharp occupies the same line that an F note would occupy. Since it is not attached to any one note in particular it dictates the treatment that all F notes will receive throughout the entire selection, that treatment is being sharped are raised one half step in pitch.therefore this key signature represents the key, the scale, of G major.

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