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Part-writing Chords: Tonic And Dominant I

It’s one thing to know what a chord is. It’s quite another to know how to use chords in music. Traditionally, chord use has been studied via the discipline of “part-writing”—the craft of creating rich harmonic textures from individual (usually sung) lines. Although it is confusing to some—not everyone finds this approach intuitive—there is much to be said for it: it is both well-known, and deeply reflective of music history.

To understand this concept of part-writing, let’s take an example. Suppose someone wants you to harmonize “Auld Lang Syne” for their New Years party, and they have helpfully supplied you with a ‘lead sheet’— the lyrics and the notated melody of “Auld Lang Syne,” with chord symbols showing which chords should accompany the melody (and where each chord should occur!)

Example 1--Lead sheet for "Auld Lang Syne."

Example 1--Lead sheet for "Auld Lang Syne."

There are many correct ways to ‘realize’ this lead sheet, but some will sound better than others. The first is one of the ‘others.’ In it, the left hand of the piano has simply been given a simple three-note ‘triad’; the bottom note is always the ‘root,’ the note after which the chord is named.

Example 2--Simple Realization of lead sheet.

Example 2--Simple Realization of lead sheet.

The result sounds clunky and simplistic. There are couple of reasons for this.

One is that the constant use of chords in ‘root position’—that is, chords with the root as bass note—and with the same voicing (the arrangement of notes above the bass)—means that all the notes of the chords are locked into the same relative positions. Thus, they always move in the same fashion.

For example, in moving from the first measure's C major triad to the G major in measure two, the ‘C’ moves up to ‘G’, a span of five notes—this span is termed a ‘fifth.’ But the ‘E’ above the ‘C’ moves up a fifth as well, to ‘B’; and the same is true of the ‘G’, which jumps up a fifth to ‘D.’ This type of relative motion, in which voices move in the same direction, and by the same amount, is termed ‘parallel motion.’

(It’s worth mentioning here that corresponding notes within a texture form ‘voices’—for example, the ‘C-G’ in the previous discussion could be called the ‘bass voice.’ This is a ‘voice’ in the abstract sense; the ‘voice’ need not be literally sung.)

A second reason for the clunky sound is that the left hand’s notes are very close together, while a much greater space exists between the left hand and the melody itself. For example, in the very first measure the left hand has three notes within the span of a fifth, but there is then an empty octave plus a fourth between its upper note, 'G', and the 'C' in the right hand.

This separation keeps a thick-sounding left hand from blending with the melody. Musicians say that such a texture has poor ‘spacing.’ In general, upper voices should not be separated by more than one octave; bass notes may be separated by up to an octave plus a fifth. (Though I must quickly add that this rule does not apply in all musical textures! Still, it is the guideline for everyday four-part writing of the sort we are discussing here.)

Here's a version that most people will agree sounds better:

Example 3--Better spaced realization.

Example 3--Better spaced realization.

In this version, the harmony notes supporting the melody—call these the 'inner voices'—are moved higher, while the bass notes are held lower, resolving the spacing problem. The result is a sound that is brighter and more focussed. The accompaniment recedes into the background, allowing the melody to 'shine.' The bass, too, is heard more clearly, and better supports the melody—even though it hasn't changed in itself!

The harmony notes also move in ways that are at once more economical and more varied. They are more economical in that they jump much less, moving more often instead by 'step'—that is, from one note to an adjacent one. (This stepwise motion makes them much easier for the listener to follow, and in the case of actual vocal parts, much easier to sing, too.) They are more varied in that their relative motion is sometimes parallel, sometimes similar—moving in the same direction but not the same distance, and sometimes contrary—moving in opposite directions.

As mentioned above, most listeners will find this version an improvement. But that doesn't mean that it can't be better yet. Compare a third version:

Example 4--More sophisticated realization.

Example 4--More sophisticated realization.

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The final version offers further improvements. We won’t go into the details at this point, other than to say that the bassline is more independent than before, maintaining a constant, even rhythm that helps propel the music forward.

To summarize, part-writing chords correctly in traditional style requires that:

  • upper voices be spaced no more than an octave apart, and that
  • upper voices move smoothly, mostly in stepwise motion without excessive jumps. (The bass part may jump more.)

If both of these requirements are not met, the sound will not be well blended, and the melody may not receive the focus it should have. (It's a little like a poorly-executed mix in popular music.)

Let’s move our focus in a bit tighter now, and look at the single most important progression in traditional harmony: the progression from tonic to dominant and back. But what do “tonic” and “dominant” mean?

As described in Chords in keys, diatonic chords fall into standard patterns which are the same from key to key. Labeling chords according to their place within the scale gives us a convenient way to discuss these patterns.

So for example, in the key of C major, scale degree 1 is the note after which the key is named—'C.' This is also called the “tonic” scale degreee . The “dominant” scale degree is scale degree 5; in the key of C, that would be the note 'G.'

Chords, in turn, are named after the scale degree which forms their root. Thus, in C, the “tonic chord” is built upon the tonic scale degree—C. And the “dominant chord,” G, is built upon the dominant scale degree. This may sound a bit confusing when explained in words. But if so, the following example should help make it clear:

Example 5--Tonic and Dominant chords in the major scale. Note that it is conventional to use Roman numerals to symbolize chords.

Example 5--Tonic and Dominant chords in the major scale. Note that it is conventional to use Roman numerals to symbolize chords.

Each scale degree has its own sound or ‘personality.’ The tonic scale degree feels stable; it is the normal final tone of conventional melodies, and signals finality or closure. By contrast, the dominant scale degree is unstable and conveys activity or energy. Similar qualities would apply to the tonic and dominant chords built upon those scale degrees.

Because these chords mark the normal extremes of harmonic tension and relaxation within a key, classical harmony has made tonic and dominant its two most important and frequent chords. There are many lengthy passages in Classical music using tonic and dominant harmonies exclusively, or nearly so.

So, how do tonic and dominant connect in traditional part-writing? That is, how do you use these chords in creating a harmonization, or a melody?

One answer to that question would be to give a set of rules describing what not to do. This is an approach often taken, and it has its value. But here we'll focus mostly on how one should write tonic-dominant chord progressions. We'll do that by identifying some three-note 'lines' which are used over and over again in music over the centuries, and showing how they can be 'mixed and matched.'

Let’s look at a few three-chord examples following the pattern I-V-I. First is a symmetrical progression in which identical tonic chords surround a dominant chord:

Example 6--I-V-I, "neighbor note" version.

Example 6--I-V-I, "neighbor note" version.

Here the upper voices—call them soprano and alto, after the voices that could potentially sing them--form what might be called ‘neighbor-note’ figures: 1-7-1 and 3-2-3. (This is another example of parallel motion.)

Even smoother is the tenor voice, which never moves away from scale degree 5. In traditional part-writing, this is called ‘keeping the common tone,’ since the ‘G’ is common to both I and V chords. Keeping the common tone is considered a desirable thing to do, but it’s not always possible--not all chord progressions have common tones, as the tonic-dominant progression does--and as we'll see, even when a common tone exists it's not always possible to maintain it in the same voice.

Finally, the bass voice outlines the roots of the chords. As such, it must leap; stepwise motion is not available to it, since the roots of the tonic and dominant chords are always a fourth (or fifth) apart. So in real music the bass line often leaps much more than the other voices.

In summary, we have four lines: 1-7-1; 3-2-3; 5-5-5; and 1-5-1. These lines, and variants of them, will be seen in many different settings. But there are other possibilities as well. The following example shows a more 'directional' realization of the I-V-I progression.

Example 7--"Passing-tone" versions of I-V-I, correct and incorrect.

Example 7--"Passing-tone" versions of I-V-I, correct and incorrect.

In this version, the scale segment 1-2-3 replaces the more static 1-7-1 in the soprano line, creating a very different character: the soprano seems to drive upwards.

This 'driving' soprano line forces adjustments to the alto and tenor lines, however: if we were to retain the ‘common-tone line’, the 5-5-5, we would run into spacing problems, as shown in the “incorrect” version on the right. (Try to hear the difference--though it may not be obvious to all listeners at first. But the badly spaced chords do not sound as well-blended and smooth; the tenor line tends to ‘jump out’ of the texture.) So our alto line becomes 3-5-5, and our tenor, 5-7-1.

Interestingly, it’s possible to convert version two into something close to version one by ‘re-shuffling’ the first chord, as shown in below. The soprano note, 'C,' would move into the tenor voice, one octave lower. The alto and tenor notes would be shifted up an octave, and into the soprano and alto voices, respectively. As we will see later, this idea of shifting lines, or parts of them, between voices can be a useful trick.

Example 8--Converting "passing-tone" version into "neighbor-tone" version using voice exchanges.

Example 8--Converting "passing-tone" version into "neighbor-tone" version using voice exchanges.

This progression also works very well in reverse, with a 3-2-1 soprano line:

Example 9--Passing-tone version, reversed.

Example 9--Passing-tone version, reversed.

Compare how this sounds, though, if the voices are reshuffled:

Example 10--Passing-tone version with exposed leading-tone (LT in the soprano.)  Not good!

Example 10--Passing-tone version with exposed leading-tone (LT in the soprano.) Not good!

For many listeners, there will be something awkward and unsatisfactory about the soprano line. This awkwardness comes about because of the characteristic sound of scale degree 7—it ‘wants’ to progress to scale degree 1, as dramatized in this example:

Example 11--Leading-tone demonstration.

Example 11--Leading-tone demonstration.

Did you feel slightly uncomfortable during the prolonged B? If so, you have learned to expect the resolution of leading tone to tonic.

Most listeners don’t mind the frustration of unresolved leading tones when they are hidden away in inner voices, but find them more troubling when found in the soprano voice (where they are heard most clearly.) That means that the awkward 1-7-5 soprano line of Example 9 should only be used in alto or tenor voices—and in fact choral Altos and Tenors get to know this line quite well, but Basses and Sopranos not so much.

There’s another common way of part-writing the I-V-I progression using this 3-2-1 line. Rather than accompanying it with lines in similar motion, as above, we can use contrary motion:

Example 12--Passing-tone version in contrary motion.

Example 12--Passing-tone version in contrary motion.

Notice how the tenor line, 1-2-3, not only moves contrary to the soprano, but actually reverses it.

One feature of this version is that it moves from what is called an “open spaced” chord—one in which the upper voices are spaced in fifths and sixths—to a “close spaced” chord—where the voices are separated by thirds and fourths.

Actually, Example 7 above did this, too, but some would say that this version does so a bit more smoothly, and might prefer it for that reason. Can you hear the difference? (Some will notice it, others won't—or not right away, at least.)

This version can be reversed by swapping soprano and tenor lines, as shown below.

Example 13--Reversed contrary PTs.

Example 13--Reversed contrary PTs.

(Here we move from 'close' position to 'open' position tonic chords—for Example 13 is the 'smoother' version of Example 9 above, just as Example 12 related to Example 7.)

Another feature of Examples 12 and 13 is that they each require a different “doubling” of the dominant chord. “Doubling” refers to the fact that when one distributes the three possible chord tones of a triad—root, third and fifth—among four voices, one chord tone will need to appear twice. In previous examples, the root of the triad has always been the doubled tone.

In this example, by contrast, the doubled tone is the fifth of the chord. Does this create problems? Well, to answer a question with a question, did you notice the difference, until it was pointed out in this paragraph?

On the other hand, listeners of the past and present have been troubled by doublings of the last remaining possible chord tone of the dominant triad--the third. That’s because the third of the V chord is also the 'leading tone' of the key. As we saw above, this scale degree has an unstable, energetic 'personality', and to emphasize it by doubling is undesirable—it is ‘too much.’

(The case is a bit different for the tonic triad. Like the dominant triad, the ‘default doubling’ is the root, with a doubled fifth an entirely acceptable alternative. But the third of the I triad may also be doubled—it is not that unstable leading tone found in the dominant! Call the doubled-third tonic chord “Plan C.”)

One last variant allows us to combine the 3-2-1 line with the 5-5-5 “common-tone” line:

Example 14--"Leaping line" version of I-V-I.

Example 14--"Leaping line" version of I-V-I.

This is less common, perhaps because it involves a larger leap in an upper voice than we have seen before. Larger leaps have traditionally required more careful melodic treatment than have skips or steps, and have therefore been used more sparingly. This soprano line is a good example of the traditional melodic treatment of leaps: the energy of the downward fourth ('E' to 'B') is compensated by an immediate stepwise 'turning-back' ('B' to 'C.') Sometimes you see this version, reversed—1-7-3—in an inner voice.

(By the way, the computer realization used in the audio/video example highlights another possible reason that this version is less common: if you are like me, your ear tends to 'lose' the 'B' within the chord, and to substitute a 'D' instead. (Presumably the 'D' is more 'expected.') In effect that's a loss of clarity, since this version is 'harder to understand' for one's musical intuitions.)

At any rate, this version is closely related to the neighbor-note I-V-I with which we began, since one can be converted into the other by exchanging just two notes:

Example 15--I-V-I with leaping soprano, and its conversion to neighbor-tone version via voice exchanges.

Example 15--I-V-I with leaping soprano, and its conversion to neighbor-tone version via voice exchanges.

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Let’s sum everything up once again.

In traditional part-writing:

1) Voices should be no more than an octave apart from each other, bass excepted. (Good “spacing.”)

2) Voices should move economically, with stepwise motion preferred over skips or leaps. Again, the bass is excepted. (Good “voice-leading.”)

3) When writing triads in four voices, one note must appear twice. For tonic and dominant chords, the first choice of doubled note should be the chord’s root; its fifth is next best; the last choice is the chord’s third. (Note: for a dominant chord, the third is also the leading tone of the key; do not double this tone!)

4) Several common lines exist for the chord progression I-V-I. These include:

  1. Neighbor-note lines, 1-7-1 and 3-2-3;
  2. Scalar lines, 1-2-3 and 3-2-1;
  3. Accompanying lines, 5-5-5 (“common-tone” line), 5-5-3 (or the reverse), 5-7-1;
  4. Bass line, 1-5-1;
  5. Leaping line, 3-7-1.

You can ‘mix and match’ these lines to create different combinations, each possessing a slightly different sound or character--though not all lines go together without creating problems in doubling, spacing or voice leading. It’s a lot easier and more efficient to take this positive example-driven approach to part-writing than to take the traditional ‘rule-driven’ negative approach.

But skill is the product of practice much more than of just understanding--it takes practice, too. Not so coincidentally, the next Hub in this series gives you a whole set of practice exercises to work through. Check it out to build your skill in applying what you've just learned here!

Practice Exercises

  • Part-Writing Chords: Tonic And Dominant I (Exercises)
    This companion to "Part-Writing Chords: Tonic And Dominant I" has practical exercises to build skill in part-writing tonic and dominant chord connections. Get to know I-V-I in many different keys and different voice leadings, one click at a time.

Other Hubs by Doc Snow


Doc Snow (author) from Camden, South Carolina on October 27, 2011:

Thanks, hh! Always a pleasure to hear from you!

Hello, hello, from London, UK on October 27, 2011:

I think it was well writing. Very explanatory and clear. Thank you.

Doc Snow (author) from Camden, South Carolina on October 24, 2011:

Thank you so much, guys! The videos are a lot of work, so I'm glad the result is helpful.

I'm hoping it will be a good resource for students of harmony. . . we'll see! (I hope it won't take too long to get that companion Hub of practice exercises together--stay tuned for that, because that's where the rubber really meets the road.)

Chas Mac from UK on October 24, 2011:

This is an excellent hub. I think it strikes exactly the right balance you were looking for. It's impressively informative while also being clear and interesting.

Lorne Hemmerling from Prescott on October 24, 2011:

Great hub, my friend!!

Doc Snow (author) from Camden, South Carolina on October 23, 2011:

I hope you found this Hub a useful introduction to part-writing--one that strikes the right balance between too much detail, and not enough essential information.

Let me know! The plan is to continue on with practice Hubs and additional harmonic vocabulary. Is that something you might find interesting? If not, what would you like to know about music and music theory?

Thanks for reading this far--and special thanks to those who offer feedback below!

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