Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man (18 page)

Real-world choreography pays attention to pitch and loudness contours as well as gait sounds; and, crucially, which pitch and loudness contour matches a movement depends on where the listener is. Choreography for pitch and loudness contours is listener-centric.

The implication for musical choreography is this: in matching music to movement, the choreographer must make sure that the
view
point is the same point in space as the
listening
point. Good choreography must not merely “know its audience,” but know
where
they are. Music choreographed for
you
, where you’re sitting, may not be music choreographed for
me
, where I’m sitting. In television, choreographers play to the
camera’s
position. If movers are seen in a video to veer toward the camera, melody’s pitch must rise to fit the video, for example. In live shows, choreographers play to the audience, although this gets increasingly difficult the more widely the audience is distributed around the stage. (This is one of many reasons why most Super Bowl halftime shows suck.)

Whereas our discussion so far has concerned rhythm and beat, which do not depend on the listener’s position, the upcoming sections concern pitch and loudness, each of which depends crucially on the location of the listener. Music with only a beat and a rhythm is a story of human behavior, but without any particular viewpoint. In contrast, music with pitch and loudness modulations puts the listener at a fixed viewpoint (or listening point) in the story, as the fictional mover changes direction and proximity to the listener. These are the mover’s kinematics, and the rest of this chapter examines how music tells stories about the kinematics.

Motorcycle Music

Next time you’re on the highway at 70 mph next to a roaring Harley, roll down your window and listen (but do not breathe!). I did this just the other day, and was struck by something strange about how the chopper sounded. The motorcycle’s “footsteps” were there, namely the sounds made by the bike’s impacts directly on the asphalt as it barreled over crevices, crags, and cracks. The motorcycle’s “banging gangly” sounds were also present—the sounds made by the bike’s parts interacting with one another, be they moving parts in the engine or body parts rattling due to engine or road vibrations. And the bike’s exhaust pipe also made its high-frequency
vroom
(not quite analogous to a sound made by human movers). These motorcycle sounds I heard were characterized not only by their rhythm, but also by the suite of pitches among the rings of these physical interactions: the bike’s “chords.” These rhythm and chord sounds informed me of the motorcycle’s “state”: it is a motorcycle; it is a Harley; it is going over uneven ground; it is powerful and rugged; it needs a bath; and so on. Rhythm and beat (and the chords with which they seem inextricably linked), the topics of much of this chapter thus far, are all about the
state
of the mover—the nature of the mover’s gait, and the emotion or attitude expressed by that manner of moving about.

What, then, was so strange about the motorcycle sounds I heard while driving alongside? It was that the motorcycle’s overall pitch and loudness were
constant
. In most of my experiences with motorcycles, their pitch and loudness vary dynamically. This is because motorcycles are typically
moving
relative to me (I never ride them myself), and consequently they are undergoing changes in pitch due to the Doppler effect, and changes in loudness due to changing proximity. These pitch and loudness modulations give away the
action
, and
that
was what was missing: the motorcycle had attitude but no action.

Music gets its attitude from the rhythm and beat, but when music wants to tell a story about the mover in
motion
—the mover’s kinematics—music breaks out the pitch and becomes melodic, and twiddles with the volume and modulates the loudness. The rest of this chapter is about the ecological origins of melody and loudness. We will begin with melody, but before I begin to defend what I think musical melodic pitch means, we need to overcome a commonly held bias—encoded in the expressions “high” and “low notes”—that musical pitch equates with spatial position.

Why Pitch Seems Spatial

Something is falling from the sky! Quick, what sound is it making? You won’t be alone if you feel that the appropriate sound is one with a falling pitch (possibly also with a crescendoing loudness). That’s the sound cartoons use to depict objects falling from overhead. But is that the sound falling objects
really
make, or might it be just a myth?

No, it’s not a myth. It’s true. If a falling object above you is making audible sounds at all (either intrinsically or due to air resistance), then its pitch will be falling as it physically falls for the same reason passing trains have falling pitch: falling objects (unless headed directly toward the top of your head) are
passing
you, and so the Doppler effect takes place, like when a train passes you. Falling objects happen to be passing you in a
vertical
direction rather than along the ground like a train, but that makes no difference to the Doppler effect. Because falling objects have falling pitch, we end up associating greater height with greater pitch. That’s why, despite greater sound frequencies not being “higher” in any real sense, it feels natural to call greater frequencies “higher.” Pitch and physical height are, then, truly associated with one another in the world.

But the association between pitch and physical height is a
misleading
association,
not
indicative of an underlying natural regularity. To understand why it is misleading, let’s now imagine, instead, that an object resting on the ground in front of you suddenly launches
upward
into the sky. How does
its
pitch change? If it really were a natural regularity that higher in the sky associates with higher pitch, then pitch should rise as the object rises. But that is not what happens. The Doppler effect ensures that its pitch actually
falls
as it rises into the sky. To understand why, consider the passing train again, and ask what happens to its pitch once it has already reached its nearest point to you and is beginning to move away. At this point, the train’s pitch has already decreased from its maximum, when it was far away and approaching you, to an intermediate value, and it will
continue
to decrease in pitch as it moves away from you. The pitch “falls” or “drops,” as we say, because the train is directing itself more and more away from you as it continues straight, and so the waves reaching your ears are more and more spread out in space, and thus lower in frequency. (In the upcoming section, we will discuss the Doppler effect in more detail.) An object leaping upward toward the sky from the ground is, then, in the same situation as the train that has just reached its nearest point to you and is beginning to go away. The pitch therefore
drops
for the upward-launching object. If rocket launches were to be our most common experience with height and pitch, then one would come to associate greater physical height with
lower
pitch, contrary to the association people have now. But because of gravity, objects don’t tend to launch upward (at least they didn’t for most of our evolutionary history), and so the association between physical height and low pitch doesn’t take hold. Objects
do
fall, however (and it is an especially dangerous scenario to boot), and so the association between physical height and “high” pitch wins. Thus, greater height only associates with “higher” pitch because of the gravitational asymmetry; the fundamental reason for the pitch falling as the object falls is the Doppler effect, not physical height at all. Pitch falls for falling objects because the falling object is rushing by the listener, something that occurs also as the train comes close and then passes.

Falling objects are not the only reason we’re biased toward a spatial interpretation of pitch (i.e., an interpretation that pitch encodes spatial position or distance). Our music technology—our instruments and musical notation system—accentuates the bias. On most instruments, to change pitch requires changing the position in space of one’s hands or fingers, whether horizontally over the keys of a piano, along the neck of a violin, or down the length of a clarinet. And our Western musical notation system codes for pitch using the vertical spatial dimension on the staff—and, consistent with the gravitational asymmetry we just discussed, greater frequencies are higher on the page. The spatial modulations for pitch in instrument design and musical notation are very useful for performing and reading music, but they further bang us over the head with the idea that pitch has a spatial interpretation.

There is yet another reason why people are prone to give a spatial interpretation to melody’s “rising and falling” pitch, and that is that melody’s pitch tends to change in a continuous manner: it is more likely to move to a nearby pitch than to discontinuously “teleport” to a faraway pitch. This has been recognized since the early twentieth century, and in
Sweet Anticipation
Professor David Huron of Ohio State University summarizes the evidence for it. Isn’t this pitch continuity conducive to a spatial interpretation? Pitch continuity is at least
consistent
with a spatial interpretation. (But, then again, continuity is consistent with
most
possible physical parameters, including the
direction
of a mover.)

We see, then, that gravity, musical instruments, musical notation, and the pitch continuity of most melodies conspire to bias us to interpret musical pitch in a spatial manner (i.e., where pitch represents spatial position or distance). But like any good conspiracy, it gets people believing something
false
. Pitch is not spatial in the natural world. It doesn’t indicate distance or measure spatial position. How “high” or “low” a sound is doesn’t tell us how near or far away its source is. I will argue that pitch is not spatial in music, either. But then what
is
spatial in music? If music is about movement, it would be bizarre if it didn’t have the ability to tell your auditory brain where in space the mover is. As we will see later in this chapter, music
does
have the ability to tell us about spatial location—that’s the meaning of
loudness.

But we’re not ready for that yet, for we must still decode the meaning of melodic pitch. My hypothesis is that hiding underneath those false spatial clues lies the true meaning of melodic pitch: the
direction
of the mover (relative to the listener’s position). It is that fundamental effect in physics, the Doppler effect, that transforms the directions of a mover into a range of pitches. In order to comprehend musical pitch, and the melody that pitches combine to make, we must learn what the Doppler effect
is
. We take that up next.

Doppler Dictionary

In the summer months, our neighborhood is regularly trawled by an ice cream truck, loudly blaring music to announce its arrival. When the kids hear the song, they’re up and running, asking for money. My strategy is to stall, suggesting, for example, that the truck only sells dog treats, or that it is that very ice cream truck that took away their older sister whom we never talk about. But soon they’re out the door, listening intently for it. “It’s through the woods behind the Johnsons’,” my daughter yells. “No, it’s at the park playground,” my son responds. As the ice cream truck navigates the maze of streets, the kids can hear that it is sometimes headed toward them, only to turn at a cross street, and the kids’ hearts drop. I try to allay their heartache by telling them they weren’t getting ice cream even if the truck
had
come, but then they perk up, hearing it headed this way yet again.

The moral of this story about my forlorn kids is not just how to be a good parent, but how kids can hear the comings and goings of ice cream trucks. There are a variety of cues they could be using for their ice cream–truck sense, but one of the best cues is the truck’s
pitch
, the entire envelope of pitches that modulates as it varies in direction relative to my kids’ location, due to the Doppler effect.

What exactly
is
the Doppler effect? To understand it, we must begin with a special speed: 768 miles per hour. That’s the speed of sound in the Earth’s atmosphere, a speed Superman must keep in mind because passing through that speed leads to a sonic boom, something sure to flatten the soufflé he baked for the Christmas party. We, on the other hand, move so slowly that we can carry soufflés with ever so slightly less fear. But even though the speed of sound is not something we need to worry about, it nevertheless has important consequences for our lives. In particular, the speed of sound is crucial for comprehending the Doppler effect, wherein moving objects have different pitches depending on their direction of movement relative to the listener.

Let’s imagine a much slower speed of sound: say, two meters per second. Now let’s suppose I stand still and clap 10 times in one second. What will you hear (supposing you also are standing still)? You will hear 10 claps in a second, the wave fronts of a 10 Hertz sound. It also helps to think about how the waves from the 10 claps are spread out over space. Because I’m pretending that the speed of sound is two meters per second, the first clap’s wave has moved two meters by the time the final clap occurs, and so the 10 claps are spread out over two meters of space. (See Figure 23a.)

Figure 23
.
(a)
A stationary speaker is shown making 10 clap sounds in a second. The top indicates that the wave from the clap has just occurred, not having moved beyond the speaker. In the lower part of the panel, the speaker is in the same location, but one second of time has transpired. The first wave has moved two meters to the right, and the final wave has just left the speaker. A listener on the right will hear a 10 Hz sound.
(b)
Now the speaker is moving in the same direction as the waves and has moved one meter to the right after one second. The 10 claps are thus spread over one meter of space, not two meters as in
(a)
. All 10 waves wash over the listener’s ears in half a second, or at 20 Hz, twice as fast as in
(a)
.
(c)
In this case the speaker is moving away from the listener, or leftward. By the time the tenth clap occurs, the speaker has moved one meter leftward, and so the 10 claps are spread over
three
meters, not two as in
(a)
. Their frequency is thus lower, or 6.7 Hz rather than the 10 Hz in
(a)
.

Now suppose that, instead of me standing still, I am moving toward you at one meter per second. That doesn’t sound fast, but remember that the speed of sound in this pretend example is two meters per second, so I’m now moving at half the speed of sound! By the time my first clap has gone two meters toward you, my body and hands have moved one meter toward you, and so my final clap occurs one meter closer to you than my first clap. Whereas my 10 claps were spread over two meters when I was stationary, in this moving-toward-you scenario my 10 claps are spread over only
one
meter of space. These claps will thus wash over your ears in only half a second, rather than a second, and so you will hear a pitch that is 20 Hz, twice what it was before. (See Figure 23b.) If I were moving away from you instead, then rather than my 10 claps being spread over two meters as in the stationary scenario, they would be spread over three meters. The 10 claps would thus take 1½ seconds to wash over you, and be heard as a 6.66 Hz pitch—a lower pitch than in the baseline case. (See Figure 23c.)