[MUSIC] That was music from George Gershwin's 1930 musical Crazy Girl and the song I've Got Rhythm. Well we've all got rhythm. Rhythm, along with melody, harmony, tone, color, texture and form, are the essential elements of music. We'll be exploring these elements in our next several sessions. We'll start with rhythm, because rhythm provides a framework, a framework in time in which sounds, pitches, can rest. We all have rhythm, of our lives, and a beat, a heart beat. And, of course, there's a beat in music too. Most music has a regular pulse to it. Some music, Gregorian chant, for example, doesn't have a beat. Here's a group of singers I organized some years ago singing a Gregorian chant at Yale University, along with an image of a chant manuscript from the Yale rare book library. In this music there really is no beat. [MUSIC] Very beautiful, but no beat. Pop music usually has a very strong beat. That's one of the things that makes it popular. We respond, almost primordially, to a beat. Here's an example of a pop piece with a strong beat, and also a strong backbeat that helps us emphasize the beat. It's a video created as a somewhat organized, or maybe disorganized, flash mob, or flash dance, recently in the main library of Yale University. [INAUDIBLE] [MUSIC] Pretty good. It's almost impossible not to tap your foot to that. In classical music, there is a beat, but it's often suppressed. It's more subdued. The rock musician, Brian Eno, who worked with the Beatles, once said classical music is music without Africa. Meaning that music without a strong rhythmic profile. And for the most part, he was right. But here's an example of classical music in which there is a pretty clear beat, Pomp and Circumstance March by the classical composer Edward Elgar. You've probably heard it at a graduation. [MUSIC] Not surprising that in this classical movement, the beat is pronounced because we're supposed to march to it during a graduation ceremony. I'd say in Pomp and Circumstance, we have a medium strong beat. But here's a much better example of what I mean when I say the classical music often has a suppressed beat. Or the sound of the beat is weak. Indeed, where is the beat here? Can you tap your foot to it like you could with the Macklemore? Here's Debussy's Claire de lune. [MUSIC] So, we have heard strong beat, medium beat, and very weak beat or suppressed beat. Beats come along in regular intervals and are of the same duration, regular beat. However, the western psyche doesn't like streams of undifferentiated anything. We group time into units of seconds, minutes, and hours to make sense of it. We group decades and centuries into periods and call them the Renaissance and the Enlightenment, to help us make sense of what would otherwise be a seemingly endless flow of time. I'm convinced that in my Toyota automobile, the safety belt alarm goes ding-ding-ding, ding-ding-ding, ding-ding-ding if I don't have my seat belt fastened. So too in music, we group the endless flow of beats to make sense of them. Here's an undifferentiated flow of beats. We can sound them with this gadget. And we've been doing that since the time of Beethoven. [SOUND] Called of course a metronome. And here's what we instinctively do. We take these beats and group them into units of two. So here are the beats. Now group into units of two, or we can group them into units of three. And of four. But in fact, in most, but not always, music written in four beats is just a multiple of music in two beats. So really, for our course, we are going to have just two beat music and three beat music. Music in duple or music in triple meter. Now, I just used the word meter there. When we group beats into regularly recurring units, we create meter in music. Meter is simply a pattern of regularly recurring beats. The lines that separate the groups are called bar lines or measure lines. Each unit constitutes a bar or a measure. Bar lines tend to make western music on a grid. Other cultures don't have this kind of grid, and as a result their music is a good deal more flexible. But we in the west, we have these measure lines, or these bar lines, and it's almost as if you can't break out from behind the bars. That you're kept inside of the measure. Okay, so we've talked about beats, and meters, and measures, or bars and bar lines. Now, let's take a look at this same material in a slightly different way, but before that, I've got a question for you. What are the two axes, or coordinates, of music? Again, what are the two axes, or coordinates of music? Right. Pitch and duration. Otherwise said, sound and time. Pitch is represented on a vertical axis in written form, and time on a horizontal one. Here's a graph to demonstrate this. Now, here's a score of a piano piece by Beethoven. This musical score is just a complex version of this previous slide's simple idea. Pitch is indicated vertically, time horizontally. How do we get from this simple idea of a two axes graph to this complex version of musical notation that you see on the screen? Well, we'll look at that in our next segment.