Aspetti psicoacustici e musicali en

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Harmony in music

Harmony, as the word itself suggests, indicates the fusion of three or more sounds (pitches) in a single musical entity, commonly called a “chord”. Different frequencies make different areas of the basilar membrane vibrate. If these frequencies are sufficiently distant (i.e. beyond their critical band), our ear can distinguish the individual pitches that make up a harmony, in the same way that our eye does with different shades of colours. Even more so, and this terrain is still partially unexplored, if different instruments execute different notes simultaneously, our ear has the "magic" ability to correctly assign harmonic partials to their respective fundamentals, allowing us to accurately distinguish and separate instrumental timbres.

The “colour” of harmony

Generally, even if we are barely trained to recognise agglomerates of frequencies and to treat them like mixtures of colours, each harmony has its characteristic morphology and a well-trained ear can easily distinguish a major triad from a minor one, an altered chord from a perfect one, a dissonant harmony from a consonant one; just as we can distinguish yellow from blue, or in an even more refined manner, carmine red from blood red. The metaphor of colours is not entirely unrelated because in both cases we are dealing with a perceptual-sensorial faculty and because artistic and cultural currents have historically supported parallels between painting and music. For example, if we think about canvases by Monet, we tend to naturally associate them with the music of Debussy that, far from being simply “descriptive”, reconstructs the same vague atmosphere, blurred edges and loss of sharpness that are typical of impressionistic painting within a peculiar musical syntax using timbre and harmony artifices.

Several chords of the tonal system
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Triade_maggiore.mp3

Major triad

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Triade_minore.mp3

Minor triad

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Settima_dominante.mp3

Perfect chord (dominant seventh)

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Settima_diminuita.mp3

Altered chord (diminished seventh)

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Triade_maggiore.mp3

Consonant chord (major triad)

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Nona_dominante.mp3

Dissonant chord (dominant ninth)

These considerations lead us to enlarge our field of research and open an important chapter regarding harmony and the creation of a harmonic syntax.

Creation of a harmonic syntax

As can be easily intuited, this topic deals with relating several aggregates of sounds according to a pre-established criterion in order to create an actual “discourse” that makes sense. Tonal language has accomplished this through a long, troubled historical process. Before going into more detail, remember that tonal syntax, being primarily of an occidental root and having originated through specific social and cultural conditions, is not the only one that exists or is possible. However, it is evident that, having “resisted” for so long without suffering problems, it is a particularly solid and effective language because it is based on theoretical laws that also fully respect psychoacoustics laws.

Tonal language

Fundamentally, tonal harmonies are composed of sounds belonging to a series of harmonics (see Consonance and dissonance) and, therefore, possess a solid, “natural” foundation that also accounts for their perceptual pleasantness. If this “pleasantness” can be considered universally valid, the same conclusion cannot be drawn about the concatenation of multiple harmonic entities, a criterion that varies depending on historical era and geographic area of origin. The guideline shared by all these trends is the aspiring to a similarity with spoken language (and all the intonation variations that distinguish it including punctuation) and the incessant search of tension towards clearly final, stable harmonies. As tension is an eminently subjective parameter (or at least highly conditioned by the socio-cultural environment in which we live), each civilisation has developed their own way of displaying it.

Cadences and harmonic successions

In tonal music, the main attraction is the interval of the ascending fourth (or the equivalent of the descending fifth) and the related triads built on the two notes forming this interval. This simple concatenation is called perfect cadence, while the succession of more than three harmonies connected by the same degree of attraction gives rise to progression (of which here are some “artistic” examples: Winter from The Four Seasons by Antonio Vivaldi, two pieces by Schumann from Davidsbündlertänze and the 3rd movement of the Quartet with Piano in E♭)). Of course, the variety of harmonic successions is quite vast and it is even possible to “harmonise” the same melody in many different ways (as happens in Frederic Chopin's Mazurka op. 30 no. 2 or in the innumerable versions of the famous song White Christmas).

Perfect cadence
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Quarta_giusta.mp3

Ascending fourth

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Cadenza_perfetta.mp3

Perfect cadence

In-depth study and links

  • If you want to know more about the solid, "natural" foundation of tonal language as it developed in the occidental music, visit the page Physical and mathematical aspects.
  • On this page, we have often spoken about intervals between two notes; if you want to know more about musical scales, visit the page From sound to music.

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