Chord types
We distinguish two basic types of chords: triads and quadriads.
The basic triads are a family of 3-note chords, whose harmonic structure is based on the harmonic intervals iA (3) and iA (4).
We call the notes of the triad components, which we represent with the letters «a», «b» and «c» in their fundamental state. The basic triads have their origin and explanation in the internal structure of the sound of a note, that is, in its series of harmonics.
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Component «c»: traditionally referred to as the «fifth» of the triad. |
| Component «b»: traditionally called the «third» of the triad. | |
| Component «a»: it is traditionally called the «fundamental» or «root» of the triad, since it represents the base of the sound of the series of harmonics represented by the triad. |
Among the components of the triads we distinguish internal and external iAs:
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| example of iAs in Major triad |
The three iA that form the triads: iA (7 4 3) are the first differentiated iA of the harmonic series.
The two internal iA that make up the different basic triads are iA (3) and/or iA (4). The 3 and 4 are divisors of the module or register 12; the iA (3) divides 12 into four parts and the iA (4) divides 12 into three parts. Due to this regular division, triads are very stable harmonic structures with a very large sonority.
They are the historical basis of the harmonic structures of traditional European music, both classical and popular.
We distinguish 2 types of basic triads:
- Asymmetrical triads have the iA (3) and iA (4) in their harmonic structure and form the basis of traditional tonal harmony.
- the major triad (tr M), follows the harmonic structure eA (3 4). It is the triad closest to the harmonic series, so its sonority is very bright.
- the minor triad (tr m), follows eA (4 3). This triad is the result of the vertical reflection of the major triad, so its sound is darker.
In asymmetric triads, the iA between the components «a» and «b» determines whether the triad is major (M) or minor (m), and the iA between «a» and «c» is in both cases iA (7), which is an iA of resonant loudness.
- Symmetrical triads have the same iA in their harmonic structure and are more dissonant and mysterious, since they divide the module or register 12 in symmetrical parts in an artificial way.
- the augmented triad (tr aug), follows the eA (4 4). This triad divides the module or register 12 into 3 equal parts.
- the diminished triad (tr dim), follows the eA (3 3). The iA (6) that is generated between components a and c, gives this triad a very ambiguous sonority.
We also contemplate three more types of triads, which are the result of modifying some component of the Major triad:
- the b5 triad is formed by altering downward by -1 the c component of the Major triad, and follows the eA (4 2)
- the triad sus 2 is formed by altering downwards by -2 the b component of the Major triad, and follows the eA (2 5)
- the triad sus 4 is formed by altering the b component of the Major triad upwards by 1, and follows the eA (5 2)
Quatriades are a family of 4-note chords: they are formed from a basic triad to which we add a new note called the «d» component.
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| example of iAs in major quatriade with 7 |
Observe the different types of basic quatriades, generated from the basic triads and adding the d component.
