Chord Voicing and the Perceived Quality of Dissonance and Consonance

     In this post I will be giving you some tips about chord voicing. In a previous article, I have tackled this subject but, as a refresher, it refers to how the notes of a chord are distributed or placed. And also, as a reminder, chord pitches may be arranged in close position (the most compact voicing), or in open position (wider spacing).

     This is important because the way you arrange the notes on chords influences the sound of how that chord is perceived – i.e. as being more or less consonant. However, the harmonic feel of the selected chord is also influenced by register. So, when the same chord is played in the different registers, while maintaining the same voicing, you will get a very distinct feel even though it’s the same chord with the same chord voicing:

     Chords are more resonant when its note arrangement is closer to the relative distances present in the overtone series, with wide spacing on the bottom and closer spacing in the upper register. In the previous example, when played in lower register, the close spaced chord became a bit muddy. A way to dispel muddiness would be to arrange the notes in a way that the chord starts with a fifth or with an octave if it’s too low in the register:

F major in low register according to relative distance present in the overtone series

     This is related to the harmonic series and it happens because the overtones created by lower pitches are more easily discernible to our hearing. As mentioned, when a note is played, it is producing its own set of harmonics. In chords, we have multiple notes at played at the same time. This means that when you play close intervals in the lower register, where the overtones are more discernible, the perception of overtones clashing with one another is also increased. In higher register, the overtones won’t be heard so easily and thus will not sound as discordant.

     To complement what I previously said, you may come across with a concept called the Lower Interval Limit. It basically states the overtone production principles and it says that, based on the frequency of the first note, how big the interval must be in order for that interval to sound clear and distinct.

     For instance, if we were to use the 440 Hz A as our base note and play the C above that to form a harmonic interval of a minor third, we would have a difference in frequencies of 83.25 cycles per second (C5 is 523.25 Hz so 523.25 – 440 = 83.25 Hz). These two pitches are clearly separated and can be perceived as pleasant.

     But if use the same pitches four octaves down, A has a frequency of 27.5 Hz and the minor third above that is a C with a fundamental frequency of 32.70 Hz. The difference between pitches is harder to distinguish because it’s only 5.2 Hz. The human ear can roughly detect frequencies oscillations as low as 2 to 5 Hz and, to illustrate, the difference between that A and A# is only 1.64 Hz. While we can still detect this difference but if played low enough it can be difficult to properly distinguish between the two notes.

The Perceived Quality of Dissonance

     Based on the above, the closer the notes are in frequency the more discordant they sound against each other. And this is the reason why a 2nd interval sounds harsher than a 9th interval because the 9th is the same note played an octave apart and thus further away in the frequency spectrum.

     It is still perceived as a dissonance because of its relation with the root tone, but a milder one. Dissonances of close intervals are thus more discernible and they are even more protruding when they are placed in the extremes of the chord arrangement – on the lower or upper parts of the chord:

 On high registers, dissonances don’t sound so harsh but are still very noticeable

    On the other hand, dissonances in mid register tend to be smoother because they are somehow enclosed, in the sense that there is more interval interaction going on besides the two notes producing the close dissonance:

     Any given note in a chord arrangement and its position in the chord layout contribute in its own way to the overall harmonic sonority and relative perception of the dissonance-consonant balance.

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