Remember those rules of part-writing we need to follow? Introducing seventh chords into the harmonic mix requires us to follow some new rules. 

First, though, let’s talk about why seventh chords might have different rules than triads. 

The Chordal Seventh 

When writing seventh chords, you will usually have four notes, each a third apart from one another. The note that is a seventh above the root is called the chordal seventh. This note is what makes a seventh chord a seventh chord, and we have some special rules related to the chordal seventh that we have to follow. 

Note that a lot of times, when we refer to the chordal seventh, we are specifically referring to the chordal seventh of the V7 chord, which is the fourth scale degree on the diatonic scale. This specific note is called a tendency tone, because it wants to resolve down to the third scale degree (just like the leading tone wants to resolve up to the tonic). Unless there are special circumstances, you should resolve the chordal seventh down – especially if it is the fourth scale degree. 

One reason why the chordal seventh is so important is that it is what creates dissonance. Consider a triad. There are three notes, each a third apart. The root is usually a perfect fifth away from the fifth, and the fifth is usually a perfect fourth away from the root if you invert the chord. Similarly, the fifth would be a sixth away from the third if you invert the chord and put the fifth of the chord below the third. 

This is notable because none of these intervals are dissonant! That means that it is relatively easy to arrange triads and use them in chord progressions without worrying about whether the triad will sound good. 

When we introduce seventh chords, we have all sorts of dissonances caused by the chordal seventh. We might have minor or augmented seconds, major or minor sevenths, etc. Thus, we need to be careful about how we deal with the chordal seventh. 

Voice Leading With Chordal Sevenths 

There are three main rules we should follow when part writing with seventh chords. 

First, chordal sevenths should almost always be approached by common tone or by step. For example, if you have a chord progression that goes from the tonic chord to the V7 chord, and you are in A Major, you know that you can either approach the chordal seventh (in this case D) from a step up with the C# or a step down with the E. 

Here is an example of how this might be done: 

Sometimes, you might be really stuck, and because of other voice leading rules, you can’t approach the chordal seventh by step. If this is the case, then in some circumstances,  chordal sevenths may also be approached by ascending leap or (rarely) by a descending leap of a third. 

Try to avoid the third option as much as possible. It is much better to use an ascending leap than a descending leap of a third. 

Why is this? Remember that when you have a leap, you want to follow that leap by a step in the opposite direction. Now, this brings us to our second rule, which is that all chordal sevenths should resolve by a descending step, to avoid an unresolved seventh. 

An unresolved seventh is just a seventh that doesn’t resolve in a satisfying way. Sometimes, composers will do this on purpose to create tension and dissonance. It is a stylistic choice. But, when you’re writing the AP Music Theory exam, you should just resolve the chordal seventh down! 

Let’s consider the example above once again. Remember that we went from a I to a V7. Suppose that now we want to go from a V7 to a vi (a predominant chord). The chordal seventh, i.e. the D, should resolve down to a C#, which is the fifth in the vi chord. 

Of course, there are exceptions to this rule as well. The first exception is if you are suspending the chordal seventh, meaning that you are keeping it the same note for the next chord. This creates additional tension and dissonance, and it is acceptable if voice leading allows. For example, suppose you are going from a V7 to a vii chord. The chordal seventh in the V7 chord appears in the vii chord as well, and so you can let that voice hold on to the chordal seventh before you resolve it down in the next chord. 

Notice how the V7 and the vii chord both have a dominant function. The suspension of the chordal seventh is actually a function of prolonging the dominant area of the harmonic progression in this case. Essentially, we try to add one more dominant chord to build suspense and tension before finally resolving to the tonic. 

The other exception to this rule is when you have a I-V4/3-I6 chord progression. In that case, you want to approach the chordal seventh by step up, and then resolve it by step up again, so you get a 3-4-5 sequence of scale degrees. Usually, this sequence should happen in one of the middle voices – not an outer voice. 

The last thing we might consider is omitting voices. Sometimes, you can omit a voice in a root position, dominant seventh chord, if it helps with voice leading. The only voice that you are allowed to omit is the fifth. If you do this, the root should be doubled. 

Writing the Voice Leading FRQs - Tips and Tricks 

When writing the voice leading FRQs on the AP Music Theory exam, there is no doubt that there are A LOT of things to keep track of, and it is easy to forget some voice leading rules. 

If you want to tackle the voice leading FRQs, it is important to first understand which voice leading rules the AP Music Theory readers are going to pay attention to. In order to do this, let’s look at the rubric. 

There are 25 points total, and they are divided into 3 categories: 

1. Roman Numerals
2. Chord Spelling, Doubling, and Spacing
3. Voice Leading

Roman Numerals is pretty self explanatory. If you write the roman numeral correctly, you get one point. If you don’t, you don’t get the point. 

Next, let’s talk about chord spelling. You will get a full point for chord spelling if you do the following things: 

1. The chord must be spelled correctly. An incorrect accidental on the wrong side of the notehead will be considered a misspelling.
2. The fifth (but not the third) may be omitted from any root-position triad.
3. The fifth (but not the third or seventh) may be omitted from a root-position dominant seventh chord.
4. All inverted triads and inverted seventh chords must be complete (i.e., have all chord tones).
5. All triads must contain at least three voices.
6. All seventh chords must contain at least four voices.

As a quick side note, when it says that the seventh chords must contain at least four voices and triads must contain at least three voices, it isn’t talking about doubling. It’s just saying that for seventh chords, two voices can’t converge on the same note. 

If you make one of the above errors, then you will also get 0 points for voice leading, meaning that you miss three whole points! Therefore, the above six rules are probably the most important.

Now, if you make a minor error, like having an octave or more between upper voices or having a correct accidental on the wrong side of the notehead, then you might miss ½ a point or maybe a full point, but you still might get points for voice leading.

There are some major voice leading errors that you should pay attention to. You won’t get any points for voice leading between two chords if:

1. Parallel octaves, fifths, or unisons occur (immediately successive or beat-to-beat), including those by contrary motion.
2. Uncharacteristic leaps occur (e.g., augmented second, tritone, or more than a fifth).
3. Chordal sevenths are unresolved or resolved incorrectly. (The voice with the seventh should move down by step, but may move UP by step only in the case of the ⅰ–Ⅴ3 4 –ⅰ 6 progression.)
4. The leading tone in an outer voice is unresolved or resolved incorrectly.
5. The 6th or 4th of the cadential 4/6 chord is unresolved or resolved incorrectly.
6. At least one of the chords has more or fewer than four voices (soprano, alto, tenor, and bass).

Don’t worry if you’re not sure what number 5 means yet. We’ll learn about cadential 6/4 chords in Unit 5! 

There are also some minor voice leading errors that you could make. They will make you lose one point (each chord can get up to two points for voice leading) 

1. Uncharacteristic rising unequal fifths
2. Uncharacteristic hidden (covered) or direct octaves or fifths between outer voices.
3. Overlapping voices.
4. A chordal seventh approached by a descending leap of a fourth or larger.

And, one last thing! If you have more than 6 leaps total (in all the voices) you will lose one point off of your total score. 

That’s all there is to it! While it is a lot of rules and it might be overwhelming at first, you now know which rules the AP readers care about and which rules they don’t care about as much! Remember this checklist, and you will ace the voice leading section of the exam.