Is "Tonal Center" Just the Key?

Harmony & Theory
#1

I just dove into the Berklee Press book of Jazz Harmony although it’s pretty dense (in good way). The first sentences of Chapter 1 begin:

Mainstream jazz harmony is both tonal and functional:

  • Tonal music has one pitch as its primary focus: a tonal center that servers as a reference point for all the other chords and melody notes in the piece.

  • Harmonic function describes the relationship of a chord to its tonal center. Chords function by creating a resolving motion around the tonic.

At the risk of being over analytical, the notion of a tonal center isn’t that well articulated here. Is the tonal center just the key? (in which case, why not just say it’s the key?). But the definition also explains how “all the other chords and melody notes” reference the tonal center. Does that mean the tonal center is a chord? (e.g. C Major and not just C?).

The book does offer an illuminating image of chords and melody notes orbiting this tonal center each with its own gravity which pulls the composition away from and back to the tonal center.

Another analogy employed is that of language:

Scale degrees [e.g. 2nd 3rd 5th] and their tendencies are like the letters of a language - the most basic unit. Next, we will look at the “words” - diatonic chords, the vocabulary of harmony. We will do this through the lens of harmonic function: the essential dynamic role each chord plays. After those basic identities are defined, we will combine them and explore the grammar of harmonic progression.

And you thought music theory was going to be difficult to learn :upside_down_face:.

There’s a suite of technical terms in this book and I am hoping to lean on this forum for assistance making sense of them. The first question is: Is the “Tonal Center” just the key?"

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#2

Based on further reading, I am arriving at a preliminary answer to my question. The Berklee Press book The Chord Scale Theory and Jazz Harmony explains

The starting note and tonal center of these scales (authentic scales) as at the bottom of the range. In traditional practice this pitch is called the Final. pg 13

This explanation is associated with a figure showing the different modal scales in the key of C (e.g. C Ionian, D Dorian…). Therefore, the tonal center appears to be the modal scale root at the bottom of the range. D is the tonal center of D Dorian, G is the tonal center of G Mixolydian.

I have taken to playing in the key of C as a way to simplify the memorization of the fretboard (no flats or sharps :grinning:). Somewhat to my surprise, even with that didactic crutch, it is still taking a lot longer to ‘know’ what note I am playing as I am playing it. While I am playing in the key of C, I typically am playing the D Dorian scale. With that in mind, my tonal center is D, not C. Therefore, I am coming to the conclusion the tonal center is not the same as the key signature.

This suggests another question. When I am playing a simple I IV V blues progression as I move from D to G, does the tonal center move to G Mixolydian and then A Aeolian (so from D to G to A) during the course of the progression? I am finding there playing the G Mixolydian and A Aeolian scales to match the chord progression is pleasing to my ears.

My hunch is the answer is “no”. The Berklee melody and harmony theory seems to assert that those G & A chords reference the D tonal center and they function to make “the music move forward and come to a satisfactory conclusion” (Jazz Harmony pg 3). That won’t work if the tonal center changes with every chord change.

#3

No, because each chord in a blues is a dominant 7th chord (not sure where you even got Aeolian from, that shouldn’t match at all). The Blues is an interesting progression because there is a lot of harmonic ambiguity going on with potential melodic choices. Rock and Blues players (especially rock players) can stick to the minor pentatonic based on the I chord because it hits the 1, 5, and b7 of the chord. The minor 3rd is where the ambiguity comes in, and where you get the bluesy tendency to bend or hammer on up to the major 3rd in a lot of blues phrases.

The major pentatonic is also an option that includes the 2, and 6, which is why when mixed in with the minor pentatonic you arrive at notes that fit with either Dorian or Mixolydian modes, and those can both work fairly well on the I chord depending on context.

When I teach soloing over the IV and the V I don’t really teach straying from key center (in your case, D, so D minor/major pentatonic scales. But what I like to do is “overlay” the notes of the IV7 and V7 chords on top of the minor pentatonic scale based on the I7.

So I’m going to use A as the key center in this example:

A7 = I7 chord, and the key center
Main scale choice = minor pentatonic

1 b3 4 5 b7
A C D E G

If you add the A7 chord tones to that, you add in the major 3rd, C#

The IV chord, D7 has the following tones:
1 3 5 b7
D F# A C

If you compare that chord to the A minor pentatonic, the only note that doesn’t match is the 3rd of the D7 chord, the F# note. So over the IV chord, you can use this “scale”
1 b3 4 5 6 b7
A C D E F# G

This is one note off from an A Dorian scale (it’s missing the 2, but the 2 won’t clash, since we know it’s also in the major pentatonic).

The V7 chord, E7 has the following tones:

1 3 5 b7
E G# B D

When overlayed on top of the A minor pentatonic, the G# clashes with the G, so I tend to just use the G in passing and mainly target the E B and D notes.

So, basically, the blues does have a key center, but over each chord you can pull notes from the arpeggios to add into your pentatonic scales.

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#4

@BlackInMind Thank you for the thoughtful response. Give me a day to two to think through your comments and I’ll get back to you.

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#5

@BlackInMind I see what your saying. It’s like each chord has a distinctive note that is both available and wants to be highlighted. Playing that note accentuates the chord. In the past, I would just play Dorian over everything but that has some disadvantages; a) the risk that all my solos sounded the same, and b) God forbid, the progression changes (e.g. other than I IV V) and I don’t know how to adjust. So I appreciate you taking the time to coach me here.

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#6

Well each chord has 4 distinctive notes - all of them! haha. I’m describing whats known as playing the changes, or outlining chords while soloing. IMO, its the hallmark of really great guitar solo writing and improvising. Whenever you hear a soloist sound like they know exactly what to play over what chord, its probably because you are hearing them play the changes. Jazz guitarists are expected to be able to do this, and real blues guitarists do this as well. Smart rock players do this, its why David Gilmour’s solos are so melodic, for example. A great easy study in this in a rock context is the first solo for Comfortably Numb.

Marty Friedman also talks about this a lot, particularly in the intro of this video:

The basic idea is that when a new chord comes up in a progression you want to land on a note from that chord. Again, check that first solo in Comfortably Numb by Pink Floyd and notice what notes Gilmour lands on when each new chord comes up.

#7

Cool thread!

One little thing I’ve learned from listening to really great jazz players on how to make this sound really smooth: when the chord changes, make the interval between the last note of chord #1 and the first note of chord #2 as small as possible. Ideally, either a whole step or half step.

For example, if you’re soloing over a D7 (D F# A C) that changes to a Gmaj7 (G B D F#), you could play the note ‘C’ on the last beat (or subdivision/upbeat) of the D7 chord. If you immediately follow this with a ‘B’ when the chord changes to Gmaj7, you’ve made only a half step in your line during the ‘change’ and taken the listener between both chords as smoothly as possible.

The possibilities are endless too. Especially if you start altering the dominant chord (D7 in my example). If you play a D7#5 (D F# A# C), you can connect the change with an A# to a B as the chords change from D7 to Gmaj7.

To me, this sounds way sexier and more idiomatic than just blowing on a D Mixolydian, then crashing into a G Ionian, starting the G mode right on a root G note, regardless of where the line ended while you were on the D mode.

You can still improvise within boundaries like this, but it will take you from chord to chord very smoothly and really craft a ‘line’ to your solo if you map out 2-note transitions like these between chord changes. If you think about it, bass players do stuff like this all the time when they walk bass lines, just typically more slowly than how we’d do it when we solo.

Verbose, wordy, and probably worth a video example but I wanted to throw that idea out while it was fresh in my mind in case it helps anyone else. For me, that concept really helped a lot, whether it’s rock, blues or jazz (or even a classical composition).

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#8

Yes the tonal center is the key. I went to Berklee. It’s a contemporary music school. Meaning modern theory(jazz not contrapuntal/classical) but in modern music there are many substitutions for diatonic chords. So just because you throw in an EbM in a song in C doesn’t change the key. Very basic but easy to over analyze. It has nothing to do with improv or soloing within the context of theory. It’s just a theoretical parlance. You still need to know chord tones and parallel/relative keys; eg; the difference between C Major/A minor/Other C based scales.

#9

I’m not sure if my view fits a proper definition of “tonal center,” but this is a topic I’ve been thinking about a lot over the past month or so and I wanted to share an observation in hopes of helping and/or learning something new.

As it was mentioned above, it’s all relative. Meaning, it’s all about how the chords relate to each other, how the notes within a chord relate to each other, and how all of those notes collectively relate to each other. All of this, I guess, is another way of thinking about what mode you’re playing in. So in the above example, obviously the note “A” comes in handy because of the I chord, but in itself “A” doesn’t really work as “tonal center” because we want a center that would distinguish “A” major from minor from phrygian etc etc etc. So I really like how the notes of each of the I, IV and V chords were laid out, since it makes clear which note are in common between all of the chords.

Now as someone who is basically new to music theory and composition, where I’m at now is that I think of the tonal center as based on where the half steps are in whatever mode you’re in. In the example above, the chord progression is A-D-E, which could be A Ionian, but the discussion clearly indicated A Dorian. Given that this is A Dorian, I would emphasize as a “tonal center” the B-C and F#-G relationship and the journey down to A from C (or the inverse) or the journey up to A from F# (or the inverse). And the G would keep our V chord (E7) grounded in a minor mood. These half steps help frame and ground the relationship between the chords being played and how we want to use harmony to express the feeling and tension that comes with straying from and returning to that tonal center. Can we use a bass line in conjunction with melody to mechanize this? IDK, but it sounds interesting.

Also fwiw, when messing around with chord inversions and “voice leading” during chord progressions, I notice that these half steps areas of the mode keep recurring when I try to play a chord sequence that involves as little re-fingering as possible.

I don’t know if any of this is correct, but these half steps seem more and more integral to the tone and feel of an overall song the more I play around with mode-specific chord progressions. I’d be excited to get any feedback on this.

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