Chapter IV: What is Harmony?
So far we have investigated the nature of sound, from how a single tone is produced and transmitted, its mathematically perfect unfolding into harmonics, to the observation and use of these harmonics as musical intervals.
The topic of this chapter is Harmony, which now takes into account the “vertical” aspect of music. As we learned in the previous chapter, an interval is the transition from one pitch to another. In that sense, one can say this is a horizontal movement of pitch in time. Harmony involves the interaction of simultaneous harmonic tones as musical chords, aligning the notes vertically in time and in the music sheet, as well.
The use of arpeggios, which are horizontal melodic lines with a harmonic structure, can also imply a given harmony even if the notes are not played simultaneously. However, this can be also regarded as harmony, rather than only melody, because the listener keeps the previous notes in memory, and reconstructs the chords in this way. An interesting example of arpeggios implying harmony is presented at the bottom of the page: The opening melodic line of Beethoven’s Für Elise is played first as a minor harmony, as was originally written, and then transformed into a major harmony.
Tones are combined to form chords, and chords are combined to form songs. When people learn to play an instrument, say a guitar, they learn a few easy chords and already they can play a large number of popular songs. My guess is that half of the popular music today is built using only three or four chords. If you want to make more interesting music, however, you will need to get a little more creative than that. Fortunately, a wide range of harmonic possibilities exist for those who want to investigate.
How many chords are necessary to make music depends on the music style. Modern day rock/pop music is usually very simplistic when it comes to harmonies, using some 4 chords per song. Even the Beatles, considered an iconic band in the evolution of rock/pop used as many as 8 chords per song, which is a considerable investment of creativity, relatively speaking. Harmonic diversity has also a cultural component. Brazilian music, as an example, has traditionally been very rich in the use of different harmonies. A typical Samba or Bossa Nova composition employs as much as 20 chords, which is about the number of harmonic changes generally used in Jazz for a single composition. Classical music is difficult to categorize with the other examples, because of the extensive use of arpeggios and counterpoint, as opposed to rigid blocks of chords. However, classical music employs every possible harmonic structure, what naturally varies from epoch to epoch and from composer to composer.
In order to categorize chords, a distinction is made depending on how many tones are used to build one. The least number of notes for a chord to deserve its name is two. These simple chords are called dyads, and are most commonly formed by the fundamental tone plus the fifth interval, which is the most important one. This type of harmony is very pure, but also very simple and quite undefined.
From Dyads to Tertians: Music Begins to Develop Personality
Adding one more note creates a chord type called a tertian. In its simplest form, a tertian is formed by the fundamental, the fifth and the third. In the context of harmony, these notes are referred to as the tonic, the dominant and the mediant, respectively. Based on our discussion from the previous chapter, one would certainly have to ask the question: which one of the two thirds? This is a very important observation, because just as there are minor and major third intervals, the median in the chord defines whether the whole harmony is minor or major! A tertian is then a more defined harmony than a dyad: it can namely be major or minor, among other categorizations.
This responsibility of the mediant to influence what type of harmony results has enormous implications in our emotional interpretation of harmony, and thus of the music that employs it. We tend to perceive major harmonies as “happy” and minor harmonies as “sad”. The reason why this is so belongs to the field of study called psycho-acoustics, and is beyond the scope of this article. Listen to the examples in the audio samples below, and you can confirm this psycho-acoustical phenomenon for yourself!
By taking different notes into account in a triad, or by adding more notes to a chord, one can create more complexity in the music, for instance by introducing tension. Tension is a very important concept in music, just as it is also used in a good novel or a good film. Without tension, music can become predictable and boring. Composers use tension in music all the time, because they know that when the tension is finally released, the music gives the listener quite a dose of pleasure.
The best known resolution of tension between two chords is known as the transition from dominant chord to tonic chord, used often as the final moment of tension of a musical composition. An example can be heard at the bottom of the page.
Keep in mind that, by definition, in order for chords to be harmonious, only notes from the harmonic set, as studied in the previous chapter, are allowed. In today’s music, however, the tones of the musical scale have deviated a little from the perfect mathematical ratios present in the harmonics, for better or for worse. This subject matter will be discussed extensively in the next chapter.