When talking about circles of fifths we consider those that could help you to modulate, i.e, to move the music to another key, and I'd like to think a little but more about this, modulation is a very important concept in music, means going from one key to another. Music would be very boring, boring and dull. If pieces remained in the same key all the time. So we find that modulations occur a lot in music, sometimes a great deal. And this keeps the music interesting, and gives us a feeling, that we're moving on somewhere. The commonest modulation, that you often hear, quite near the beginning of a piece is to the dominant. So for example, a piece in F major might move to C major quite soon in the, its course. So for example, the well known Christmas Carol, While Shepherds Watch Their Flocks By Night goes like this. [MUSIC] And we're now in the dominant of C major. If you really wanted, you could even modulate that to A minor, it would sound like this. [MUSIC] Now it sounds slightly more forced, perhaps not quite so natural. But anyway, the, that illustrates the concept of modulation; going to a different key. s, these are quite definite modulations; where the new key is established quite firmly. But we also find many instances of. Keys simply being hinted at. Rather than a true modulation taking place. We find that a key is suggested. And again, this gives the music interest. And means that we feel we're moving somewhere. And one of the commonest of these involves a chord, which we usually call this. Secondary dominant, which means a dominant 7th of dominant generally. And you find this towards the end of a piece, as I said gives greater color, greater variety to the chord progression. And can again, make the cadence sound more final, and more satisfying,. If for example, we return to the progression already mentioned, iib7, V, I, that sounded like this. [SOUND] That's iib7, V, I in G Major. If we make one alteration. In the bass. Rather than C natural [MUSIC], if we change that to a C sharp [MUSIC], it sounds like this [MUSIC]. What we've created there is actually the dominant 7th in the key of D major. [MUSIC] But in this case, it doesn't go to D major, it just suggests D major and goes- [MUSIC] immediately to G. But you get that extra color. And so its hinting at a new key but not actually modulating to it. Many composers have used this, Bach is an example, for example the choral "Wie schon leuchter der morgenstern" ends like this. [MUSIC] He could have ended. [MUSIC] And that would sound perfectly good, but this added secondly dominant. Makes it just a bit more interesting. [MUSIC] Where we've hinted at another key, without actually modulating. Another example of the secondary dominant. And can be found in the tune Blackbird which ends [MUSIC] There we're in g major and the third last chord is the secondary dominant. Which suggests. Again, D major, but actually- [MUSIC] immediately comes back to G. So here it is again. [MUSIC] A move to the sub-dominant key often occurs later in the piece. Because it helps emphasize the feeling of coming home. Sometimes composers actually modulate to the sub-dominant, other times they simply hint at it. If we're in the key of C. [MUSIC] The sub-dominant chord is F. [MUSIC] The sub-dominant scale involves the note B flat. [MUSIC] And if we want to give the feeling of having moved to the sub-dominant that B flat is an important note to introduce. So for example, if you were towards the end of a piece in cee, you might hear this. [MUSIC] By introducing that B flat, which is one of the notes of the scale of f, the sub-dominant. [MUSIC] And doesn't enter into the scale of C. [MUSIC] That B flat helps you to think you're. to, that B flat gives you the flavor of the sub-dominant. So here's the progression again. [MUSIC] And you find this quite frequently towards the end of pieces. Either of a hint of the sub-dominant, or something slightly stronger. A famous example of it can be heard towards the end of the prelude by Bach. The prelude in C from book one of the 48 preludes and fugues. And he introduces the B flat just towards the end, to give the feeling of. Hinting at F major, not actually going to F major; but hinting at it. And thus giving a sub-dominant leaning as we sometimes call it. So the chords at the end of this piece sound like this. [MUSIC] Once again. [MUSIC] And we'll finish by hearing the complete prelude in C, played on harpsichord, as it would have been in Bach's own day. [MUSIC] [BLANK_AUDIO]
