In Unit 6c, we first looked at some basic rules for voicing a chord in a four-part chorale style. These rules included:
In addition to the voicing rules, there are a number of standard part-writing errors that should be avoided as well:
Please note that these errors must be within the same two voices across both chords. Due to the effects of consistently doubling roots, there will almost always be consecutive perfect octaves and perfect fifths between two triads, but this is not parallel. For example, a root position C major triad moving to a root position G triad will have two voices on C in the first chord and two voices on G in the second chord, if standard doubling practices are observed. This is fine as long as its not in the same two voices in both chords (e.g. soprano and bass both have C and then both have a G).
Each of the four primary categories of part-writing errors are symptoms of voice-leading issues. If you understand the underlying voice-leading issues of each of these errors, you can find them more easily and avoid them in your own part-writing.
Part-writing errors result from poor voice-leading. For example, look at the progression below and try to find our first major error: parallel perfect octaves (PP8). Once you have found it, look to see if a voicing rule (e.g. spacing, doubling, etc.) has been broken. If the voicing error is not fixed, is there any way to avoid the parallel octaves without incorrectly resolving a tendency tone?
Parallel perfect octaves and perfect fifths undermine the independence of lines, so you should always avoid them in this style. Listen to the following example, and try to locate the parallel perfect fifths aurally before you look through the parts. Once you have identified the voices that contain the PP5, try singing the upper of the two voices, and then listen to the example again. Do you have a difficult time differentiating the upper voice from the lower of these two voices?
In summary, you may never have parallel perfect octaves or parallel perfect fifths in this style of music. Please note that for an interval to be considered parallel, the interval must occur consecutively in the same two voices. For example, if your first P8 is between the bass and alto, the second P8 must also be in the bass and alto. If you find a P8 between the bass and tenor on the second chord, this is acceptable because it does not undermine the independence of the voices.
Our next part-writing error, contrary perfect fifths and contrary perfect octaves (CP5 or CP8) are simply an attempt to cover up parallel perfect fifths and parallel perfect octaves by displacing one voice by an octave. The next two examples attempt to fix the errors from the first two examples on this page by displacing one voice of the parallel perfect intervals. Identify these by comparing them to the previous example (i.e. P) Notice that it creates multiple voicing and spacing errors as well as nearly unsingable parts!
Again, remember that for this to be considered an error, the contrary perfect octaves/fifths must be in the same two voices. If the interval changes voices, it does not undermine the independence of the voices.
The last two common part-writing errors have specific clauses tied to them that specify which voices are acceptable and unacceptable. The first, unacceptable unequal fifths (UU5), must occur between the bass voice and one of the upper voices. In the following example, find the unacceptable unequal fifths where a d5 moves to a P5. What is wrong with the voice-leading here?
So for this course, we will consider a d5 moving to a P5 unacceptable unequal fifths, but we will consider a P5 moving to a d5 as acceptable–a P5 to a d5 does not require incorrect resolutions of tendency tones. Remember that these errors are best thought of as symptoms of the actual problem. In this case, the real issue is that the only two notes in a diatonic key that can form a d5 are ti and fa, and as discussed many times in this course, these two notes will imply a dominant harmony that wants to resolve inward with ti moving to do and fa moving to mi. For a d5 to be followed by a P5, it would mean that fa must resolve to sol which is poor voice-leading and therefore the error we are trying to avoid. There are some stricter versions of chorale part-writing that do not allow any form of unequal fifths.
The final common part-writing has many names, but we will use the term unacceptable similar fifths or octaves. This error can also be called “direct”, “hidden”, or “exposed”. I prefer to use similar because it implies the motion like the other categories, but I also think that exposed does a fine job describing the effect. (I dislike the term hidden because students often confuse this with contrary fifths (or octaves), because the goal of contrary fifths is to “hide” parallel fifths.) Unacceptable similar fifths or octaves have the most restrictions. The conditions are:
If any one of these conditions are not met, then there is not a part-writing error. Look at the following example to find an example of similar octaves. Once you have found it, look at the voice-leading around it. What does it do to spacing? Does it create more errors? Unacceptable similar octaves and fifths also often create melodies that imply different harmonies. To demonstrate, sing the melody alone. Do you hear it as C major or a different key?
As a final demonstration of the difficulties that these part-writing errors create, try to fix each of the part-writing errors on this page. What do you have to change? Do you get to keep the harmony? Voice-leading? Voicing? In trying to fix it, do you just create further errors?
The class found two examples of parallel perfect octaves in this example.
Almost all unacceptable examples of parallel octaves and fifths are due to poor voice-leading and voicings. In this case, the third of the five chord is doubled. This third is a tendency tone that should resolve upward by step, but in doing so, it creates parallel perfect octaves. The third never should have been doubled.
In this example, the class found two examples of parallel perfect fifths:
From this, we decided that the definition of a parallel perfect fifths/octaves is:
Parallel perfect fifths and octaves undermine the independence of the individual voices. Even after listening to the example with PP5s repeatedly, only one person in the class was able to distinguish the tenor voice. I then had the class look at the tenor voice and practice singing it in order to get the line into their ears. Even after doing this, they had trouble distinguishing between the two voices. This is even more pronounced if the chords are tuned using just intonation, because the upper note will blend into the overtone series of the lower note.
Contrary fifths and octaves occur when trying to mask parallel perfect fifths and octaves. In the example above, the class identified the CP5s between bass and tenor voices between:
From this, we decided that the definition of a contrary perfect fifths/octaves is:
Unacceptable unequal fifths are one of the easier part-writing errors to understand, because we are actually focusing on only one voice-leading issue. We defined a UUF as any time a d5 between the bass voice and another voice moves to a P5. Because it has to fill all of these conditions, it is relatively easy to find compared to parallel and contrary fifths/octaves which are not acceptable between any voices.
The voice-leading issue that causes UU5 centers around the one naturally occurring d5 in the major scale: when ti is below fa. This is only likely to happen on a dominant harmony which means that this occurs typically on a V6/5 chord or a viio chord. The problem arises when fa does not resolve downward to mi in the next chord. This is an incorrect resolution of a tendency tone, and that is what creates the part-writing error.
Similar fifths/octaves occur when 1) the soprano and bass voices 2) move in similar motion to a 3) perfect fifth/octave, and 4) the soprano voice has a skip of a third or larger. You can see an example of this between the first two chords in this example.
Similar fifths/octaves are sometimes called “exposed” fifths/octaves, and both of these terms demonstrate a key feature about the part-writing error. Obviously, they must move in similar motion, but the term “exposed” highlights the fact that these must occur between the outer voices. By having similar motion to a perfect interval in the outer voices, it creates the impression of a parallel perfect interval. Most importantly, the leap in the soprano typically creates a poor soprano line in which the melody outlines/implies an unintentional harmony. In the example above, if you sing the melody line without the harmony it outlines A minor instead of C major.