[MUSIC] As mentioned, when most of us listen to music, we listen to the top line, where the melody resides. That's where the clearest and most memorable music is to be found. But to hear the harmony and the structure of the piece it's best to get down with the base. Chords are build upon a base pitch. The base determines the foundation of the chord and the direction of the harmonic progression. Some pop musicians such as Paul McCartney and Sting, well, they sing the melody at the same time they lay down the basis of the harmony by playing the electric bass, the electric bass guitar. To hear the base and to begin to focus on the harmony, let's build out three musical examples. We'll start with a piece that has only four chords in it, but they repeat over and over so that makes the harmony even easier to hear. Any harmony or melody or even rhythm that repeats again and again is called an ostinato, from the Italian word meaning obstinate thing. The piece in question is an old favorite of mine from the 1960s. It features voices, this style called doo wop. Here's what the bass sings as you can see on the screen. [MUSIC] And of course we can add chords to that. [MUSIC] In that fashion, notice major, [MUSIC] minor, [MUSIC] major, [MUSIC] major triads. And then it just keeps on looping. [MUSIC] Now, let's listen to a bit of this recording. Notice that a new chord comes on each downbeat. That's one of the reasons, as we've said, that we hear these as downbeats. Chord changes often signal downbeats. So why don't you sing along as we enjoy Gene Chandler and the Duke of Earl? [MUSIC] Great fun. All right, so you're now fully qualified to join an a cappella doo-wop group because you can sing the baseline and track the harmony. But let's move on to a more complicated example of hearing a harmony from the realm of classical music. Likely, you've heard of this piece also. It's the Canon of Johann Pachelbel, Pachelbel's Canon. The term canon in music is simply a fancy word for round. A piece in which one voice starts out and then the others duplicate it exactly, as in the well-known Three Blind Mice or Row, Row, Row Your Boat. With Pachelbel's Canon, we have a double delight, because although there is a canon, or round, in the upper three parts, the canon is supported by an ostinato bass underneath. A harmony that repeats again and again. Let's talk first about the bass. Here it is on your screen at one pitch level. But I'll play it actually at a pitch level that Pachelbel wrote it. [MUSIC] Okay, eight chord ostinato bass that repeats over and over and over. So let's now focus on the upper three parts of the score. Again, as produced courtesy of our California friend Steve Malinowski. You don't have to read or understand the specifics of musical notation to get a sense of what's going on here. Pretty simple. One voice, the leader, starts out, and then the other voice follows along immediately thereafter, at the time interval of one measure, playing exactly the same thing in terms of rhythm and pitches as the leader. And then the third voice comes in and does the same. That's what creates the canon or the round. The irony is that in the Pachelbel Canon you don't hear the canon, or at least it's not as obvious as one would think, because all three of the upper parts are played by the same instrument. They're assigned to the violin, so they have the same musical timbre or sound. They're in the same range. They're sort of right on top of each other. So there's no separation of the individual parts, which makes it difficult for the listener to actually hear the canon. But if we look at the music as we listen, we can see the unfolding of the canon. Let's watch. [MUSIC] Bass line with implied harmony being played above. Now, leader voice. [MUSIC] Follower one. [MUSIC] Follower two as leader goes on to play quarter notes. Shorter vowels. [MUSIC] Follower picks up the quarter lengths. [MUSIC] As follower two picks up the quarter lengths, reader goes on to play eighth notes. [MUSIC] Follower one, eighth notes. [MUSIC] Follower two picks up the eighth notes. [MUSIC] Hey, heads up because the leader's going to begin with 16th notes. [MUSIC] Gives the impression that they're all [INAUDIBLE] but the music is gathering momentum, even though the tempo is completely stable, completely steady. As you can see by the pulse of the notes above. Finally, the most sophisticated example yet, of harmony, a piece by JS Bach, a prelude for keyboard. Here, ironically, there's no melody. There's just a harmony. [MUSIC] But what he's done is taken those chords of the harmony and spread them out as arpeggios. [MUSIC] This independent harmony does not repeat. It's not an ostinato bass harmony, as in our previous two examples. It unfolds continually. This is one long chord progression in the tonality of C. And I might add that the original version of this, arguably one of Bach's most famous pieces and in Bach's hand, for the most part is actually in our own Yale University library. Bach was trying to teach his first child, Wilhelm Friedeman Bach, how to play and how to compose and here's the way it originally looked as you see on the left side of the screen. The hand on the upper left, that's the hand of the son, Wilhelm Friedemann, and Bach came along and tried to move things along by just prescribing chords that should be played toward the bottom right of the score. With the implication that they were to then be executed as arpeggios. So, again, this is Bach's harmony without any melody. But, more than 100 years later a French composer, Charles Gounod, came along and added a melody to Bach's harmony, the two together being even more rich and pleasing than Bach's original harmony. A text was added to it, Ave Maria, turning it into a religious work, the Bach Gounod Ave Maria. And Bach's piece, originally just a harmony, is sung today at weddings and funerals around the world. In the YouTube clip that you're about to hear, Bach's harmony is being played on the piano. And you will see Gounod's melody as a score. I will play the melody, so we've got YouTube playing the harmony and I'm playing the melody. YouTube is playing Bach, I am playing Gounod. Let's see if we can pull this off. [MUSIC] Darn. [LAUGH] Almost a shame to stop, but we've got to. So, there we were, we were hearing the best of both worlds. Bach's original harmony supporting Gounod's later melody. Pretty amazing.