The term’ voice-leading’ is one coined by the American musicians and derived from the German word ‘Stimmführung’ which means part-writing. This, to me, makes considerably more sense than the above term which is why I mention it at the start of this article. With the definition in mind, it is simpler to understand what is intended by the concept of voice leading and the array of rules that are attached to it.
These, in turn, have developed through the long course of Western Tonal Music and are often compulsory study for young and old academics alike. There are clear merits for a study of voice leading rules as a composer, but unless one is stepping into musicology the benefits compositionally could only lead to avoidable frustrations.
Voice leading or part-writing then is directly connected with the idea of counterpoint. In the late 16th Century, for example, there were five ‘species’ of counterpoint each with strict rules that governed how music should be written. These rules indicated compositional elements that should be employed in very particular ways.
How for example voices could move in terms of step or leap; the use of dissonant and consonant intervals that occurred between each voice or melody; which parallel intervals between voices that are acceptable. These are only a handful of rules that dictate voice leading and therefore counterpoint.
The Council of Trent played a significant part in the construction and implementation of many of these harmonic principles. The Catholic Church was represented by the Council of Trent and dealt with the musical practices of the day and clearly outlined their expectations of composers of the time. This historically was part of the Counter-Reformation that followed Martin Luther’s nailing of his ninety-five to the Wittenburg church door in Germany (1517), and directly prising open the Catholic Churches firm grasp on Western Europe.
What comes out of this religious upheaval is that the Word of God should never be overshadowed by the music. This directive meant very specific musical rules were put upon composers of the time that shaped the direction of all music to come.
To bring a little more clarity to this complex exploration, an example of part-writing or voice leading would by a Chorale by Bach. A Chorale would be the setting of a religious text, usually for four separate voices; commonly, Soprano, Alto, Tenor and Bass.
I am deliberately using a vocal example here as many of the voice leading rules are linked to writing for actual voices. This perhaps offers a musical perspective on what can appear to be a stark set of out-dated compositional principles. Even though Bach broadly followed the rules laid down years before he was also a composer of immense creativity and as you would expect, he interpreted and adapted where he saw fit.
In the Chorale writing, it would be expected for a composer such as Bach, avoid certain practices and by avoiding them create a composition that sounded good. Naturally what constitutes ‘good’ is highly subjective but the underlying principles of these rules make musical sense.
Avoiding parallel octaves and fifths between the voices in a chorale was very important as that sound was considered to be unpleasant. This would mean, for example, the soprano and the alto singing a C and a G respectively that rose to a D and an A.
Another sensible instruction was to avoid voices moving great distances by asking singers to sing difficult intervals. Certain intervals, like a seventh or even a sixth, can be challenging whereas a melody that largely proceeds by step is easier to perform.
In addition, crossing voice parts were also frowned upon unless specifically for some kind of special effect. In practical terms, it also has merits as it is difficult to perform vocal lines with sustained overlaps between the parts.
Many other directives exist that are there to ensure clarity and harmonic integrity in a composition. The interval of an augmented fourth for instance was a strict rule as this interval was described as the ‘devils interval’ because if you invert it the interval remains the same.
It is also a highly dissonant interval that alone does not relate directly to a given key. An illustration of the augmented fourth would be E to Bb. Bach finds clever ways to use this interval in his work to create tension and resolution that is always tastefully handled.
Doubling the ‘leading note’ is a practice to avoid. This would mean, in the key of C major, not writing the note ‘B’ in more than one voice at a cadence point. The leading note is the 7th note of the key in which you are writing. When you hear a piece that ignores this rule it does sound odd.
Likewise, harmonically it makes little sense to double the third note of a chord. (In the chord of D major, for example, this would be an F sharp). Instead, it is suggested, double the root note of the chord or the fifth. The effect of doubling the third is to make the harmony less stable whereas the addition of a root note strengthens the progression and supports the tonality.
Another key aspect of all the many voice-leading instructions is the resolution of dissonance. Dissonance is the description of a sound that is felt to be unpleasant. In contrast, consonance is a sound thought to be pleasant. What sounds pleasant to one person may not sound pleasant to another but by and large, the intervals of a third, fourth, fifth, sixth and octave are considered to be consonant. All other intervals are not.
It may be reasonable to imagine Mozart hearing piece by Pierre Boulez and covering his ears in shock at the extreme levels of dissonance Boulez employs in his scores. This is because following the breakdown of tonality atonal music paved the way to a whole new way of thinking about music and one that the Council of Trent would have rejected categorically. Resolution of dissonance then is a vital part of part-writing where there is a careful balance applied between the sour and the sweet sounds of music.