A.2. The Time Signature

The dialog box that appears when you choose File New in GarageBand appears in Figure A-1. For the Time setting, GarageBand proposes 4/4 ”but whats that?

Turns out it's closely linked to the concept of measures.

Figure A-1. The New Track dialog box is the very first thing you see when you create a new GarageBand piece ”which is too bad, considering it's one of the few places that could fluster musical newcomers.

In a house, a builder may hold up the roof by installing a beam (a rafter) every eight feet. Music has underlying support structures, too ”the beats in a measure. Beats are the clicks of the GarageBand metronome, your foot -taps when you're listening to something catchy, and the "One! Two! Three! Four!" that a rock band leader shouts before a song.

Not all songs contain the same number of beats per measure. Waltzes, like "Take Me Out to the Ball Game," "A Natural Woman (You Make Me Feel)," and ”of course ”"(Once, Twice,) Three Times a Lady" have three beats per measure. In GarageBand, you'd hear the metronome go, CLICK -click-click, CLICK -click-click, and you'd hear a dancing teacher say, ONE -two-three, ONE -two-three.

Most pop songs, though, have four beats per measure. In fact, in most kinds of music, four-beat measures are the world's most popular type. If you were to chant,"one, two, three, four," rhythmically, over and over again, songs from "Fr re Jacques" to "Born in the USA" and "Oops, I Did It Again" will fit your counting.

So how was the inventor of sheet music supposed to tell you how many beats are allowed to fill each measure of music? One attempt may have looked like the top of Figure A-2.

Figure A-2. Top: Here's one way to tell musicians that there are going to be four beats in each measure of this song. But it's not terribly compact.
Bottom: Over time ”possibly about 30 seconds ”instrumentalists began to shorten this notation into something more concise . The modern time signature begins to emerge.

Now, one way to fill up the four beats in a measure is to play four quarter notes , so called because, obviously, it takes four of them to fill up one measure. A quarter note is one of the world's most popular units of rhythm (see Figure A-3).

In most songs, your foot naturally taps out quarter notes ”but not in all songs. Consider Jesu, Joy of Man's Desiring , a famous Bach piece that you can hear right now, if you like, by switching into iPhoto and listening to it. (It's one of the preinstalled background music tracks for slide shows.) In this piece, each measure has nine beats ”but they're not quarter notes. They're notes that last only half as long, so they're called eighth notes. You can see what eighth notes look like in Figure A-3 at bottom.

Figure A-3. Top: All of the notes in this part of "Fr re Jacques" are quarter notes. The kick drum of a rock band playing disco is pounding out quarter notes, too. And in the Grid pop-up menu (the little ruler at the upper-right of the GarageBand window), "1/4 Note" is one of the choices ”and now you know what it means.
Bottom: It takes two eighth notes to fill up the time of one quarter note, so they often come in pairs. And when they come in pairs, musicians connect them with a beam to make them easier to take in at a glance.

Back to Giuseppe, the sheet-music-inventing monk. How was he supposed to indicate what kind of note (eighth note? quarter note?) gets a beat?

Clearly, the one number at the beginning of the song (Figure A-2) wasn't enough information. The next step was to tell players what kind of note gets a beat ”what kind of note they should tap out with their feet ”by adding a second line under the first (Figure A-4).

Figure A-4. Top: Here's one way to tell musicians to tap out quarter notes with their feet.
Bottom: In the interests of saving space, though, another abbreviation emerged.

A time signature , then, is the 4/4 at the beginning of a piece of sheet music (or 2/4, or 3/4, or even 6/8) or in the New Project dialog box in GarageBand. It tells you two things. The upper number tells you how many beats each measure has (four beats). The lower one tells you what kind of note (quarter note).

Armed with this information, may you have the courage to try changing the Time pop-up menu the next time you create a new GarageBand piece. As the old saying goes, all 4/4 and no 6/8 makes Jack a dull boy.