Tonality (or harmonic field) is a group of chords created through a specific scale. Take like example C major scale: C, D, E, F, G, A, B.

For each note in the scale we will create a chord. We will have, then, seven chords, the will be the chords of the tonality of C.

 How will we create this tonality?

For each note in the scale, the respective chord will be created using the first, the third and the fifth degree (starting to be counted in this note, in this same scale). Let’s start with the C note. The first degree is the C itself. The third starting in C is E. And the fifth starting in C is G.

The first chord in the tonality of C is created then by the notes C, E and G (pay attention that this is the C chord, because E is the major third of C).

 Now let’s create the chord of the next note, which is D. The first degree is the D itself. The third starting in D is F. And the fifth starting in D is A. Then, the second chord of our harmonic field is created by the notes D, F and A (pay attention that this is the Dm chord, because F is the minor third of D).

 You should be realizing that until here we are creating the chords in the harmonic field thinking in triads and using only the notes that appear in the scale in question (C major). After creating the triad, we should see if the third of each chord was major or minor. You can also check the fifth of each chord, but you will see that will always be the perfect fifth, with exception to the last chord, that will have a flatted fifth. It is a good exercise to try to create the remaining chords in this tonality. After that, check the table below:

 tonality

Song Tonality

Very good, you learned how to create a harmonic field. But what does this serve for? Well, a harmonic field serves for many things, and in this moment we will focus in the most basic point: it serves to define the central note (tonic) of a song. This depends on the existent chords in this song. If a song has the major chords of the harmonic field of C, it means that the song is in C major. With this we know that the scale to be used to make a solo, to improvise or create riffs in this song will be the C major scale.

Therefore, to know the harmonic fields it’s really useful: this knowledge allows us to know the notes that we can use to do arrangements in such song. Knowing well the scale shapes, nothing will stop us to create solos and riffs automatically (ability known as improvisation).

 I hope that this has motivated you to go on in our study about tonality, seen the importance and use of this knowledge.

We have already created a harmonic field using triads, and now we will enlarge this concept to tetrads. The rule used to create the chord, just to remember, it was to take the first, the third and the fifth degrees of the scale in question. We will do the same thing, but including the seventh degree, that characterizes the tetrad. We will have then a harmonic field equals the previous one, but created by tetrads instead of triads.

Analyzing the same scale of C major, starting by the C note, we have the seventh degree of this scale, which is B. The other degrees (third and fifth) we already saw which ones they are. Therefore, the first chord of this harmonic field will be formed by C, E, G and B. This is the C7M chord, because B is the major seventh of C.

Applying this same rule to the next note (D), we will see that the seventh degree is C. Then, the chord will be formed by the notes D, F, A and C. This is the Dm7 chord. Pay attention that here we have the minor seventh of D, this is why we use the symbol “7” instead of “7M” (that characterizes the major seventh).

 Creating the complete table we will have:

 c major tonality

Maybe you are asking yourself what is the difference, from the practice point of view, of these two harmonic fields that we created. Well, the only difference is that this second one has one more note in the chord, making them more “complete”. In a point of view of improvisation, relating to discover which the tonality of the song is, nothing will be changed. We will see some examples of this subject (discovering the song tonality) soon. Before, remember that we used the C major scale. Instead of specifying the tonality (C) now, let’s take this more generic: “harmonic field of a major scale”, because if we use this rule to G major scale, A major scale or any major scale, we will always have something in common. The major tonality of any note will follow this formation (where the Roman numbers refer to degrees):

I7M   IIm7   IIIm7   IV7M   V7   VIm7   VIIm(b5)

You can check this creating the harmonic field of the remaining tonalities (besides C, that we have already done).

 Take as an example the E major scale and its harmonic field (tonality):

 E major tonality

You can see that the major first degree was with seventh, the minor second degree with seventh, etc. Following the formation that has been shown before:

 I7M   IIm7   IIIm7   IV7M   V7   VIm7   VIIm(b5)

This makes our life easier; because it means that memorizing just this sequence above you already know the major harmonic field of any note. It is just to put the notes of the major scale in question in place of degrees.

 For example: What is the major harmonic field of D?

D7M   Em7   F#m7   G7M   A7   Bm7   C#m(b5)

 Observation: The major D scale is: D, E, F#, G, A, B, C#.

 As exercise try to create the major harmonic field of all the notes. Check then the tonality table below:

 tonality table

Observation: To create the harmonic field using just 3 notes (triad), it is just remove the seventh of all the chords in this table. We will leave the seventh here only in the last chord, because the chords with diminished five rarely appear without the seventh in practice:

 major tonality table

Now that we know the major harmonic field of all notes, we can apply this knowledge to discover the songs tonality.

 Exercises:

The chords below compose some specific songs. You should identify in which tonality each song is:

 1)   A, C#m, D, Bm, E7

2)   F#m, G#m, B, E

3)   Bm7, GM7, Em7, F#m7, D, A7

4)   G, D, C

5)   Am7, Bm7(b5)

6)   Bb, F, Dm7, C7

Answers:

1) A

2) E

3) D

4) G

5) C

6) F

It is important to highlight that some songs have more than one tonality. In this case, part of the song is in one tonality and another part of the song is in another tonality. This is really common in rhythms like Jazz, MPB, Bossa Nova, Fusion, among others.

To do improvisation adequately in songs that have a lot of variation of tonalities (modulations) is a big challenge, but don’t worry. Step by step we will grow in the subjects in a way to explore more resources. With commitment and dedication, you will (in a few time) feel yourself comfortable even when you face more sophisticated sounds. We are working for that.

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