Music Composers Unite!
Parallel Motion: To Use or Not To Use - written by Ben Newhouse.
It’s an age old question…
“Is parallel motion between two voices OK?”
This often takes the form of a heated discussion between a music teacher and a student. Most likely, the teacher has said something along the lines of…
“Don’t use parallel fifths.”
This is followed by a Bach-style harmony assignment. The student, somewhere in there, uses some parallel fifths and gets scolded.
The student then gets annoyed, walks up to the piano, and pounds out a few bars of his favorite rock song. Parallel 5ths and octaves abound.
“See! It sounds good!”
Somewhere, Bach rolls over in his grave and the teacher can sense his unsettled soul.
For my part, students bring up the topic frequently.
“Are parallel fifths OK?”
So the following is my two cents on the topic. I’ve taken to answering that question in a bit of a long-winded manner. My answer, if you want to skip the details, will be, “If you want those parts to be perceived as independent voices, then no. If you want them to be perceived as a single voice, then yes.”
(Disclaimer: this blog post is my ***opinion***. So if you’re taking a test or something, don’t assume that your teacher will agree with me.)
So for a moment, let’s think about this logically…
First, what does parallel motion accomplish?
The answer is that parallel motion reduces the independence of two voices.
Let’s suppose you have two melodic lines that exist simultaneously. One is an ascending C major scale. The other is a descending C major scale. Those are two *very* independent voices and the listener would perceive them as two separate musical ideas.
Next, let’s suppose you have two melodic lines. The first is an ascending C major scale that begins on middle C. The second is an ascending C major scale that exists simultaneously, just an octave higher. The listener would perceive them as a single idea—an ascending C major scale.
In these and all cases, parallel motion reduces the independence of the two voices in question.
Second, why does the “parallel fifths are bad” rule exist?
The rule originated in music where the independence of voices was very important. In a four-part fugue, the independence of the voices is what gives the music momentum and forward motion. The voices fight against each other, building and building, until that tension is resolved at the end with a cadence.
Parallel motion in the middle of such a fugue would weaken the counterpoint and lessen the building tension. This contradicts the very point of the musical idea.
So…what are we to learn from “the rule”?
If independence between two voices is valuable in a given musical context, then parallel motion between those voices should be avoided. However, if for some reason the composer wishes the two voices to be perceived as a ***single musical idea*** by the listener, then parallel motion is not a problem.
Situation 1 – A 4-Part Fugue
The very point of a fugue is to build tension using four independent voices. If, somewhere in the fugue, you have parallel octaves or parallel fifths between two of the voices, then you have reduced the independence of those voices. You would end up with a 3-part fugue at that moment.
That would be a definite no-no. Fugues depend on keeping those voices independent, creating rhythmic and contrapuntal tension that builds as the piece progresses.
Situation 2 – A Melodic Doubling
Let’s suppose you are writing an orchestral masterpiece. You put a melody in the clarinet and you double it up an octave with a flute. Essentially, this is “parallel octaves”.
Is it a problem?
In such a situation, you want the two voices to be perceived as a single entity by the listener. You don’t want the audience to perceive a melody and a countermelody. You want them to perceive a ***single melody***, played by clarinet and flute. Since you want the two voices to be perceived as a single idea, parallel motion is perfectly fine.
Situation 3 – A Melody and a Counter-Melody
Let’s suppose you are writing a brilliant film score. You have a sweeping melody in the violins and a countermelody in the horns. Likely, you have some harmonic parts in the low strings and low brass. For a couple of beats in the middle of a phrase, you have the violin melody and the horn countermelody move in parallel fifths.
Is this a problem?
In this case, you want the voices to be independent. Here, you want the listener to perceive a three-layered texture–melody in the violins, countermelody in the horns, and harmony in the low strings/brass. When you use parallel motion between the horns and the violins, you fall back to a two-layered texture, which would be undesirable in the middle of a phrase.
Situation 4 – A Climax following a Contrapuntal Build
Let’s suppose you are writing along in 4-part counterpoint. All of those lines are creating a lot of rhythmic tension. You’re enhancing that by adding instrumentation, such as some percussion rolls and brass. At the end of the phrase, you arrive at a huge climax. Here, you come out into big parallel octaves.
Is this a problem?
The act of going from four contrapuntal lines to a single melodic line can be very dramatic. This is particularly useful at the “climax” of a piece or at the end of a contrapuntal section. In this case, you are using the reduction in voices for a musical effect—to cap a climax. At such a climax you would want the listener to perceive a single musical idea and parallel motion is OK.
(Of course, had you used parallel octaves a couple of measures earlier—where the contrapuntal lines were being used to build tension—that would be a no-no.)
Situation 5 – Background Keyboard Part
Let’s suppose you are the keyboard player in a rock band. You’re back there jamming. There is also a drummer, a bass player, a guitarist and some vocalists completing the ensemble. You want to go from a vi chord to a IV chord. You do so, using some “turn Bach over in his grave” parallel fifths.
Is this a problem?
In that situation, I’d argue that the listener perceives the keyboard part as a single entity—background chords in the keyboard. The point of the keyboard part is not to create rhythmic tension using perfect counterpoint in its inner voices. You have a drummer to create the needed rhythmic momentum (and the keyboard chords probably come in a rhythm as well…along with the bass and guitar).
Rather, the musical function of the keyboard part is to provide a harmonic foundation for the melody. As the writer, you want the listener to perceive the keyboard part as a single entity—background chords in the keyboard. In such a case, parallel motion is fine.
The key points are:
1) Parallel motion between two voices reduces the independence of those two voices.
2) If the effectiveness of the musical idea depends on those two voices remaining independent, then avoid using parallel motion.
3) If you intend for the two voices to be perceived as a single idea by the listener, then parallel motion is fine.
Parallel is an acceptable form of voice-leading, but it's not always the best choice. In the context of an orchestration it is very common to have parallel voice leading in one section of the orchestra and "real" voice leading in another. You could also have this with a piano accompaniment where the left hand is playing parallel structures and the right hand plays voice-lead structures.
This is a link to a piece that I wrote that has voice-lead structures in the treble (mostly triads moving in half or whole steps - but NOT parallel) and the bass structures are basically parallel (1-5-10 or 1-7-10):
Here's the score if you're interested:
Parallel motion is a useful tool in many compositional situations ( except during the study of early common practice Harmony 101 and 102 ) Later on , the Impressionists revelled in using it ( i.e. DeBussys' "Sunken Cathedral " )
I often use parallel seconds, fourths, clusters of linked intervals, ( two pair if major seconds ) I've even used chromatic parallel five and six voiced clusters ! ( usually referred tot as a "thickened line "
Even more useful are these same materials when used in contrary or oblique motion.
Duke Ellington ( and later Thad Jones ) regularly employed vertically stacked pairs of diminished chords ( Gerald Wilson refers to this as "octotonic voicing" ) and I too often employ this trick!