Understanding tonality (Sonata-form, Part 4)

Tonality: The sense of being in a key, or:
You know more about music than you think

DAN COREN

Fourth in a series of articles explaining sonata-form.

What does being in a key mean? And what does it mean to be in a specific key, as in “Mozart’s Symphony # 36 in C major”?

If you have any interest in music at all, you probably have a sophisticated knowledge of this concept, even if you think you don’t. Just think for a few seconds about the Christmas carol, “Joy to the World.” Hear the first line (“Joy to the world, the Lord is come”) in your imagination and— even if you’re one of the distressingly large number of people who love music but are scared of their own voices— pick any old note out of the air and belt it out.

The particular notes you sang to get from “Joy” to “Come” are what’s called a major scale. It doesn’t matter whether or not you know what a scale is exactly. But I urge you to stop and marvel at the extraordinary organizing power of those magical eight notes, especially the power the scale has to imbue one particular note with a sense of “homeness.” The note you sing when you reach “Come”— the low end of the scale— is clearly home base, the only possible note the tune could end on. (Try singing, “Come” on the same note as “Is.”)

Any music that makes one particular note sound like home base in this way is tonal. It’s “in the key” of whatever that particular note happens to be. The home note is called the tonic. It’s really that simple.

Nobody else understands it, either

There are many other ways to define a tonal center: There’s the minor scale, which uses a slightly different set of notes and which for many people has a different emotional ambience (sing “Joy the World” again, up until “Come,” and then, starting on that same note, sing “God Rest Ye Merry Gentlemen”). Jazz and blues have their own ways of doing it. Flamenco has yet another. Gregorian chant, likewise. But for now, we’ll stick with the major scale. It’s the properties of the major scale that, more than anything else, make classical music sound classical.

Believe it or not, nobody really understands why the major scale or tonality in general works as they do. And nobody is even close to understanding why some people don’t care about it one way or another while others find the scale and the system of tonality it has engendered an endless source of emotional and intellectual sustenance.

(A marvelous book— Daniel Levitin’s This is Your Brain On Music— lucidly deals with this problem in layman’s terms. Levitin’s chapter on pitch perception and scales is the best treatment of the subject I’ve seen.)

Why do keys have names?

There is no simple answer to this question.

The amazing ability of the major scale to create a key depends solely on the relationship among its notes. You’re able to sing “Joy To The World” or any other tune you know just by starting on whatever pitch comes into your head. You might need to hunt around for a note that’s comfortable for your voice; and if you sing with more than one person, you’ll both need to agree on a starting pitch; but you don’t need to know anything about the specific properties of that note.

Over more than a millennium, however, our culture has, by fits and starts, evolved an extremely peculiar and complicated system, in which we use 12 pitches, and only 12, from the infinite set that’s available. (Since our classical music tradition evolved from Catholic liturgy, the impetus for this system— it seems clear to me, anyway— was the Church’s desire to codify and prescribe liturgical practice.) The pitches of the major scale we use are named A through G (although they only sound like a major scale if you start on C). The five other pitches are named in relationship to the letters: F-sharp, D-flat, etc.

Some people– Levitin says about one in 10,000– can identify pitch names the way most people can identify colors. They are said to possess “perfect pitch” or “absolute pitch.” It’s hard to imagine that Mozart, Beethoven, etc. lacked this gift, although no hard evidence exists one way or the other.

A very short introduction to harmony

I had a good reason for asking you to imagine “Joy to the World” before you tried singing it. I’ll bet that, instead of just imagining a simple tune, you heard in your inner ear something like this excerpt (sung by the Robert Shaw Chorale)–
simultaneous melodic lines combining to form blocks of sound– chords— that magically combine to create an even greater sense of tonality, of being in a home key.

You don’t need any special training to appreciate the effects of classical harmony.

Here’s a simple melodic fragment that I wrote using a program called Finale Songwriter. (This passage happens to be in C major— that is, it uses the C major scale. But, again, its behavior depends on the relationship among its notes, not what specific notes they are.)

Here it is again with an added bass line. This is the very essence of what makes Western music sound the way it does: two independent voices working together to define a key. Between them, these two voices use all the notes of the major scale. Note how the presence of the bass line makes the behavior of the melody– especially its last three notes– seem inevitable.

Now I’ll add a third voice, and, finally, a fourth, each time using notes exclusively from the C major scale. If you can hear all four voices as independent lines, congratulations— you should consider a career in music. But for most people, I think, there’s a threshold beyond which all the combined voices blend into a mass of sound. I can hear the three voices clearly enough, but, even though I wrote them, I can’t really keep track of four voices at once.

Why they call it the dominant seventh

Yet even if you can’t sort them out individually, notice how that bass line dictates the behavior of all the voices above it. The work of defining the key is performed by the next-to-last chord and the chord before that; they make the arrival at the final tonic note inevitable. Even if you didn’t hear that last chord, you’d know what it should be. Here’s the end again, slowed down.

That next-to-the-last chord is built over the fifth note of scale, a note within the scale that has magical properties in music theory. That chord— the one that has the musical electric charge that wants so badly to discharge into the tonic— is called a dominant seventh. Knowing its name really buys you nothing, but its effects lie at the heart of classical music and, especially, sonata-form.

Some Mozart at last

Here, (finally!) are two passages from the Mozart’s Linz Symphony: the first, from the beginning of the exposition, where we left off last time; the second from the end of the exposition.

Each passage is unequivocally anchored in a key. You can listen to either example and easily find its home base. But are they in the same key? Do they have the same home base?

Having trouble deciding? Here are excerpts from the two sections juxtaposed. As a matter of fact, not only are they not in the same key, but the new tonic is the same note that was at the bottom of the dominant chord in our previous four-part harmony example. Somewhere along the way, Mozart has taken the chord that inevitably gravitated towards the original tonic, C, and made it into a new tonic. In short, the music has changed key— or, to use the technical term, modulated. In fact, the exposition of the Linz does what virtually every single sonata-form exposition in a major key before Beethoven’s Waldstein sonata does: it modulates to the dominant.

How did Mozart do it? Here's the music following the beginning of the exposition. Somewhere in this passage, Mozart makes the dominant lose its gravitational pull on the tonic and, by the end of the passage, he has made it into the new tonic. See if you can hear where it happens. I suggest you find home base at the beginning, sing it, and see how long you can hold onto it as the music progresses.

It's not so easy to hear, is it? In fact, it's very hard to say exactly where the modulation happens. It's not until a little bit later that I'm really convinced that we've reached a new home key for sure. The moment that nails it for me is the music following that loud chord in the middle of the clip.

Like a routine grounder to the shortstop

Truth be told, modulation to the dominant in a sonata-form exposition is subtle and often seems to be done by sleight of hand. Nor does it tend to be the most dramatic aspect of the form. So why am I making such a big deal out of it?

Look at it this way: Modulation to the dominant is to sonata-form what the routine ground ball to shortstop is in baseball. "Swing, and there's a bouncer to short. Rollins has it on a few hops, throws to first in plenty of time, and there's one down." The play looks easy. Harry Kalas makes it sound easy. But "plenty of time" means, typically, a quarter of a second. And throwing from short to first is anything but routine. Only a tiny fraction of the millions of kids in the world who play baseball will ever be able to make that play even once, let alone game after game, month after month.

A good shortstop's skills are the glue that holds a baseball team together. The analogous skill in writing a symphony is the ability to write a seamless, routine modulation to the dominant. It's a skill that Mozart, Haydn and Beethoven never tired of practicing, and, as we'll see as we go along, it's the move that sets up the great dramatic moments later in the form.


To read the previous article in this series, click here.
To read the next article in this series, click here.