Last Friday I tried to answer a couple of improvisation questions I was emailed by Michael. He also asked some other very good questions about my Jazz Improvisation For Beginners article on the blues form.
In your “Part 3 – the Blues Form” – something seems off. You say: “Let’s look at a 12 bar blues in the key of C.” You then go on to give the chords C7, F7, Dm7, G7, and the note Bb. I have not heard of a B7 or C7 in the key of C. Nor have I ever seen a flat or sharp in the key of C. But there is a Bb, of course, in the key of F. And the 12 bars you give clearly resolve to the F chord, not the C chord, at least to my ear, which is pitch-perfect. Isn’t this really the key of F? Or am I not understanding something here?
As I was putting together a response for Michael I found my answers relied heavily on being able to hear the musical examples, so I decided that a podcast format would be the best way to follow up. It went a little long, almost 17 minutes, but I started with a brief summary to make sure that most listeners could follow along.
Here’s a link that should give you a direct download so you can listen to it on an MP3 player. Transcript after the break.
Hi, this is Dave Wilken. In response to a three part series on jazz improvisation for beginners that I put together for the Online Trombone Journal, a reader named Michael sent me some great questions. In trying to organize the best response to some of these questions I realized that it’s much easier to explain using actual sounds, rather than writing it out. So here is a podcast response for the following questions from Michael.
In your “Part 3 – the Blues Form” – something seems off. You say: “Let’s look at a 12 bar blues in the key of C.” You then go on to give the chords C7, F7, Dm7, G7, and the note Bb. I have not heard of a B7 or C7 in the key of C. Nor have I ever seen a flat or sharp in the key of C. But there is a Bb, of course, in the key of F. And the 12 bars you give clearly resolve to the F chord, not the C chord, at least to my ear, which is pitch-perfect. Isn’t this really the key of F? Or am I not understanding something here?
These are great observations, particularly from someone who I think is largely self taught. What you’re noticing is the difference between diatonic chords and chromatic chords. The particular relationship of the chords used in a blues chord progression is part of what gives the blues an instantly recognizable sound. But before I can explain this in detail, I should give a review of some important terms and concepts. This will move pretty quickly, so if you don’t already understand something you might try searching on the internet for a music theory site that explains these principles in more detail.
When musicians use the term “diatonic” they mean that a particular pitch fits the key the piece is in. In C major, for example, the diatonic pitches are just the notes in a C major scale.
Audio Example
A “chromatic” pitch is a note that is outside of the key signature. In C major, a chromatic pitch would be any note that has a sharp or flat. A chromatic pitch has a definite sound to it when heard in context. Listen to the same C major scale and right afterwards I’m going to play a chromatic pitch. It probably sounds outside of the established key the scale sets up in your ear.
Audio Example
Chords can be diatonic and chromatic too. Diatonic chords are made up of only diatonic pitches. Going back to the C major scale, I can form triads, or three note chords, by playing every other note.
Audio Example
Here are now in succession all the diatonic triads in the key of C major.
Audio Example
When analyzing a harmonic progression it’s very common to use roman numerals to label the diatonic chords. The triad based on the first note of the scale is labeled with a roman numeral I, the second with roman numeral ii and so on up to the vii. But if we listen closely to each of the triads you can hear that there are different types of chords because a major scale is made up of different combinations of half steps and whole steps. The I chord is major, and has a sound we associate with happiness. When the I chord is analyzed with a roman numeral, it uses a capital I.
Audio Example
In contrast, the ii and iii chords are both minor. If you listen to them out of the context of a chord progression they might have a sadder sound to them. In order to distinguish them from major triads, we use lower case ii and iii as roman numerals.
Audio Example
The IV and V diatonic chords are back to major triads, so those are notated as capital IV and capital V for roman numeral analysis.
Audio Example
The vi chord is minor again. Something good to know is that this is also the relative minor key. That means that A minor, the vi chord in C major, also uses the same key signature of no accidentals.
Which leaves us with the sole example of a diminished triad, the vii chord. When analyzing this chord with roman numerals, it’s written as lower case vii followed by a small circle, the symbol we use for a diminished chord.
Audio Example
You can pretty much play random diatonic chords and they will sort of fit together in an interesting way.
Audio Example
But centuries of tradition have led to a specific sort of “harmonic gravity” of chords. The I chord will have the most restful sound to a given chord progression while other chords will want to either lead towards the I chord or away from it. The V chord, for example, has a very unstable sound in the harmonic context and wants to move to the I chord, even though they both happen to be major triads. This is called an authentic cadence or sometimes a V I cadence.
Audio Example
The IV chord, also a major chord, can move back to the I chord. You’ll recognize this particular cadence if you sing hymns. It’s called a plagal cadence.
Audio Example
Even though both the IV and V chords can resolve back to the I chord, the V I progression has a more resolved quality to it. In fact, the IV chord can just as easily lead to the V chord too, making for a very common chord progression.
Audio Example
So far all I’ve been dealing with have been three note chords, or triads. Going back to playing every other pitch in the scale to create diatonic chords, we can make each chord a 7th chord. Playing each diatonic 7th chord make for different types of chords, but essentially the chords want to move in pretty much the same way as when we use just diatonic triads.
Audio Example
One way to make the V I authentic cadence have more weight to it is to make the V chord a V7 chord by adding that 4th diatonic tone to the chord. In the key of C, the V7 chord is G, B, D, and F, or in lead sheet notation written as G7.
Audio Example
The V chord is the only diatonic 7th chord of this particular type. Because the first three pitches create a major triad and the interval between the root and 7th is a minor 7th this chord is frequently called a major-minor 7th chord, but more commonly a dominant 7th or even just a 7 chord. Let me just play the 3rd and 7th of this chord only and listen to the sound.
Audio Example
This is a particularly dissonant interval to our ears. It wants to resolve and it just so happens that both these pitches, B and F in the case of a G7 chord, can get to pitches in the C major I chord by moving just a half step. The B will conveniently move up to C while the F will move down to E.
Audio Example
Putting this in context with the rest of the chord sounds like this.
Audio Example
This chord motion is extremely common in tonal music, so it should at least sound familiar to us all.
If you’ve been able to follow me so far, then you should now be able to understand my detailed answer to Michael’s blues questions. If some of it is confusing you, you might want to go search the internet for some music theory pages before moving on. Still, after playing a lot of music most musicians develop an intuitive understanding of this stuff, even if they don’t completely know the historical context and the formal terms.
So now let me finally get to the blues, but I’m going to again take some smaller steps towards the final answer. First I have to define the blues form. There are lots of variations on the blues form, but the simplest way to describe it is the blues is a twelve bar chord progression that is based on the I, IV and V chords. Listen to a very simple variation of the blues here.
Audio Example
In that example I simply played the diatonic triads and left out the 7 chords. This next example is essentially the same chord progression, but I’m going to make the V chord a dominant 7 chord.
Audio Example
Just as in my earlier demonstration, this just adds a little more weight to the V I resolution.
Now let me demonstrate a trick that we can do to give a little more weight in the change from the I chord to the IV chord in the 4th and 5th measures. In the key of C, the IV chord is an F chord. Let’s for a moment remove ourselves from the key of C and instead think about the key of F major. As Michael mentioned in his questions, F major has one diatonic pitch that has an accidental, B flat. Also, the V chord in the key of F happens to be a C chord. If we create a diatonic 7th chord in the key of F on C we get C, E, G, and Bb, or a C7 chord. This is our V I authentic cadence in the key of F.
Audio Example
So one way we can beef up the change to the F chord in our blues in C is to add a Bb to the chord on the preceding measure. We’re creating a chromatic chord in this measure, because B flat is not diatonic to our key.
Audio Example
This also happens to be an example of what is sometimes called a “secondary dominant” and the chord motion temporarily gives us the sound of being in a different key. To take this a step further, we can just simply start the blues progression on this secondary dominant. Our tonic chord now takes on a sort of unresolved quality also and gives the overall chord progression a certain color that we associate as a bluesy sound.
Audio Example
Taking this concept even further, let’s now listen to a blues progression that also makes the IV chord 7th chord. A diatonic 7 chord in the key of C would make the IV chord an F major triad with a major 7th added, E natural. But since we’ve already established that the tonic chord is somewhat unresolved, we’re going to give the IV chord also a sense of instability by lowering the E to Eb and making the IV chord also a dominant 7th chord.
play example
Making the I, IV, and V chords all dominant 7th chords like this gives the harmonic progression as a whole a particular color that results from the unresolved quality of the I and IV chords. This harmonic feature is part of what gives the blues progression its particular sound. Many tunes that aren’t strictly based on a blues progression also exploit this same quality, which can be heard in lots of tunes in jazz, rock, country, and the blues genre.
Before I finish, I want to also describe how the two chromatic pitches that get used in my simple examples can also be used to improvise melodies. Again, using a blues in C as an example, the two chromatic chords are C7, which has a Bb, and F7, which has an Eb. The Bb and Eb are both chromatic to the key of C. Harmonically, the use of these pitches in the chords lends the chord an unresolved but bluesy feeling.
What’s interesting is that these same two pitches can be used at any time in the chord progression to give the melody a similar bluesy sound to it, even when the chromatic pitch doesn’t fit the actual chord. Out of the context, this sound awfully strange, like when I play a Bb on top of an F7 chord.
Audio Example
But in the context of a blues progression, playing those non-diatonic pitches gives your improvised melody a tension that mirrors the unresolved harmonic feeling in the blues progression. Here’s an example.
Audio Example
These particular chromatic pitches are two examples of what are often referred to as “blue notes.” Both blue notes and variations on the blues progressions are used extensively, not just in the blues genre, but also jazz, rock, country, and has even found its way into some classical music written in the 20th and 21st centuries. Hopefully my explanations and demonstrations have been clear enough that you can now recognize these sounds when you hear them again as well as begin to apply them in your own music when you’re after a similar color.
If you’ve got other questions or comments on this podcast please visit my web site at wilktone.com where you can view a transcript of this podcast and leave a comment or contact me privately.
