Blues harmony: why b7 on chord 4?

I’ve recently discovered IFR method and I’m enjoying it a lot — although I’ve just scratched the surface, it has given me more than years of memorizing pentatonic boxes. :slight_smile:

I’ve also started working on the Blues Mastery course (now at lesson 3), and while I feel b7 works well over the 4th chord, I don’t understand why we consider it a part of the “harmonic environment” of 4D.

With 1D it’s clear: b7 is just a part of the chord, but with 4D there’s nothing that seems to impose this. Why don’t we retain 7 as the part of 4D in our analysis?

Can someone clarify why we go this way thinking about the harmony here?


@wadcom I think the short answer is that “it doesn’t have to be but it typically is in most Blues improvisation”. It’s not a law, but a convention or tradition or idiom, or whatever you want to call it. Most people tend to do it most of the time, unless you play with a group of guys who don’t do it that way.

The cool thing about music is that there are really no rules. Instead there are agreements like "here’s the constraints we’re going to use to play this tune together, 4/4 time, 120 bps, key of Bb, this chord progression, etc. There are a zillion ways to make such agreements, not just the one way many music books lead you to believe.

Yes, I do understand that it works that way (I feel that when I improvise over these chord changes). I was just curious for the reasoning why @ImproviseForReal (?) chose to view that scale as containing b7 (although he could go either way…).


Hello @wadcom and welcome to the forum.

I have the Blues Mastery material but not really got into it yet. I’m still working my way through the book and other stuff, but I will get back to it.

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Welcome to the forum @wadcom

Yes, that’s the way to ‘tag’ David Reed. :slight_smile:

As @hender99 says, there are many ways to do things. The choice of tending to use 7 or b7 when in the 4D chord in the melody path diagram is one of those things. The best way for you is whatever way you feel is best!

Hi @wadcom, welcome to our forum! You’re asking a great question. And honestly, you have as much right as I do to come up with your own answer. As @hender99 said, there are no rules in music. The only role of music theory is to try to describe and organize what human beings are already doing. And in the blues, the most common scale played over that 4D chord would include b7. So this raises the question that you are asking: why?

My own attempt to explain this (which I stated in both the IFR book and the IFR Blues Mastery Course) is that in the blues, we never hear the 1 chord that comes from the major scale. In other words, we never hear the first harmonic environment like we study in Seven Worlds. Right from the start, the tonic chord appears as 1D. So this establishes the scale 1, 2, 3, 4, 5, 6, b7 as the basic harmonic environment of the song.

Then when the 4D chord comes along, you’re right that it doesn’t require us to play b7. But by the same reasoning, it also doesn’t require us to play a natural 7. So if we’ve already been hearing the b7 from the 1D chord, why should that change when the 4D chord comes along?

As I also stated in my book, it doesn’t really matter very much whether you find this explanation convincing. It doesn’t amount to much more than mythology. Trying to explain why the b7 sounds so natural to our ears in that moment is like trying to explain how the zebra got its stripes. One could imagine all sorts of imaginative explanations, but we don’t actually need any of them.

We already have everything we need with the mere presentation of a couple of different groups of sounds. One group of sounds is the 4D harmonic environment that we find in most jazz standards, which indeed has the natural 7 that you were expecting:

4, 5, 6, 7, 1, 2, b3

Another group of sounds is the 4D harmonic environment that we find in the blues, which has the note b7 as follows:

4, 5, 6, b7, 1, 2, b3

I think that the impulse to try to explain the origin of common music practices is a healthy one. It’s natural to try to find the logic or meaning contained in these choices. In music, that mostly takes the form of simply noticing when one set of sounds reminds us of something else. Whenever you find a set of notes that is surprising to you, there is almost always a very simple logic explaining the relationships between those notes, and this logic usually comes from some other chord or scale from another key which we are merely “copying” and superimposing here.

But as improvisers, it’s not really our “job” to have to come up with any convincing explanation for WHY certain sounds are played more than others. Our job is to get to know ALL of the sounds, and then create our own culture by expressing the sounds that WE want to express. So I feel that the best thing you could do with your current fascination for this topic is to take this opportunity to experiment with both the b7 and the natural 7 over the 4D chord, and just notice for yourself what effect each sound has on the music.

Remember also that the chord column drawings that you see in the IFR learning materials were never intended to limit your melodic choices to those notes. All of that harmonic analysis is merely our attempt to give you a roadmap of the sounds that we think you will find to be most consonant in each moment of a song. In other words, the IFR chord columns are like a roadmap of the underlying harmony of a song. But they do not in any way limit your freedom as an improviser to paint whatever sound you like over that canvas.

In my own life, I don’t know if I can even remember the last time that I improvised over a blues without playing both the b7 and the natural 7 over the 4D chord at some point. As both improvisers and composers, we always have all 12 notes of the chromatic scale at our disposal at all times. And once you’ve gotten to know all of these sounds, it’s hard to resist playing all of them. :slight_smile:


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Hey David, thanks for you response! I was on vacation, hence the delay…

With your book and the courses you have convinced me already that the primary task
for us is to experience music, not over-analyze it. After spending some time playing over those changes I’ve found out that all those notes just constitute a palette of sounds I can use, and there are no hard rules on when to use which sound. For example, I like how b3 sounds over the 1D chord, so I frequently use that.

It still makes one wonder why we chose those particular colors for our palette. :slight_smile: I remember when I first started, it was a complete mystery to me why they would throw both major and minor pentatonics over the same progression. With your approach it makes much more sense, so I’m trying to pick the analysis approach as well.

…but anyways, I understand what you’re saying, thank you for your response and for IFR!