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Thread: My theory on 7th chord consonance

  1. #1
    Senior Member caters's Avatar
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    Default My theory on 7th chord consonance

    So, you know how there are 6 7th chords most commonly used in music and 12 that are theoretically possible? Well, I have played around with these 7th chords, and I can say for sure that I have a specific ordering of them as far as consonance and dissonance goes. And here is that ordering from most to least consonant:

    • Minor seventh
    • Major seventh
    • Dominant seventh
    • Minor major seventh
    • Half diminished seventh
    • Diminished seventh


    Now, my theory on the consonance and dissonance of seventh chords relies on tendency tones. There is one seventh chord that might seem out of order here, but, I will get to it in due time. Now first, I have to define a tendency tone, otherwise everybody will disagree with my theory. A tendency tone is a note that wants to resolve by half step.

    Starting with the minor seventh:



    None of these notes want to resolve by half step, so none of them are tendency tones. Thus the minor seventh is the most consonant seventh chord. This is in fact, the only seventh chord that has no tendency tones. The rest of them have at least 1 tendency tone. The minor seventh provides an ambient, relaxing quality.

    Major seventh:



    Now, this seventh chord has a single tendency tone, the seventh itself. The seventh wants to resolve to the root and so the chord as a whole wants to resolve to the major chord it is based off of.

    Dominant seventh:



    Out of all the seventh chords that exist, this one is the most common. It has 2 tendency tones as opposed to the 1 tendency tone of the major seventh. The seventh is still a tendency tone, because now it wants to resolve to the third of the next chord. The third is also a tendency tone, wanting to resolve to the root of the next chord. So, the dominant seventh is more dissonant than the major seventh.

    Minor major seventh:



    This is the major outlier, not just in rarity, but also in the tendency tone to dissonance correspondence. Technically speaking, this chord only has 1 tendency tone, just like the major seventh. And like the major seventh, the tendency tone is the seventh. But this chord is way more dissonant than the major seventh. That probably has to do with the minor chord base. So, just as CM7 wants to resolve to C major, CmM7 wants to resolve to C minor.

    Half diminished seventh:



    Now, this chord has 2 tendency tones just like the dominant seventh. The root is a tendency tone and wants to resolve to the new root. The third isn't a tendency tone, but the fifth is a tendency tone with the fifth wanting to resolve to the new third.

    Diminished seventh:

    This chord takes seventh chord dissonance and tendency tones to the max. Because of the 2 overlapping tritones, a single diminished seventh chord is very dissonant, even more so when it moves to another diminished seventh. And, every single note in the diminished seventh is a tendency tone, because every note wants to move by half step.

    So, what do you think of my tendency tone theory on the consonance and dissonance of seventh chords? Do you agree with my seventh chord ordering from most consonant to most dissonant?

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    Junior Member MAXSWAGGER's Avatar
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    Do your catch yourself sometimes, asking yourself, how much music you could have created instead wasting your lifetime with this pseudo-eliterian theoretical-********-bingo ? I'm just curious...

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    Senior Member Bwv 1080's Avatar
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    Not wanting to waste time reading this before you answer the question - why do think any of this is your original theory? And if it is, why is it better than existing theory?

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    Senior Member mikeh375's Avatar
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    Other resolutions of 7ths are available (or can have alternative 'tendencies') and the dim7th tones can resolve by more than a semitone depending on context. Don't deny yourself options by straight jacketing voice leading in this manner.
    Do keep learning however, ultimately it's a great way to creatively free yourself if you acquire technique in the right spirit.
    Last edited by mikeh375; Jan-03-2020 at 06:46.
    New website and some new music......www.mikehewer.com

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    Senior Member Woodduck's Avatar
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    The "tendencies" of chords and their components depends on musical context. A chord may be more or less stable, more or less inclined to resolve into something else, depending on the style and structure of the music. In some contexts, your first four examples may stand unresolved and be heard as having no tendencies. This is characteristic of jazz, and even Chopin threw the major seventh into the final major chord of one of his preludes without setting up any need for resolution, removing from the seventh its usual tendency.

    I can't recall any music in which diminished and half-diminished seventh chords are heard as actually stable, but they can resolve in so many different ways that they can be used to create an effect of permanent instability, of complete ambiguity or a suspension of tonal function - that is, in such a way as to make any particular resolution unnecessary, canceling out any tendencies.

    Unintentionally, perhaps, you're inviting discussion of the different senses of "dissonance" - acoustic, functional, subjective. We've had that discussion around here.
    Last edited by Woodduck; Jan-03-2020 at 07:10.

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    Senior Member EdwardBast's Avatar
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    Quote Originally Posted by Bwv 1080 View Post
    Not wanting to waste time reading this before you answer the question - why do think any of this is your original theory? And if it is, why is it better than existing theory?
    While agreeing with the sentiment , the even more fundamental question, to me, is: Does this "theory" have any practical applications? Any explanatory value? Does it actually meet the definition of a theory? Or is this more like the obsessively repeated speculations on the instability of the major scale and so on that have been so pleasantly absent from this forum for several weeks?

    Edit: Oops, I looked. There are also obvious errors:

    The 7th in the minor 7th chord (first example) is usually a tendency tone by the OP's definition. If it is ii7 in B-flat major, for example, it wants to resolve down by half-step to A.
    Last edited by EdwardBast; Jan-03-2020 at 13:51.

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    "Tendencies" is itself a specialized sense in certain contexts where dissonance must be "resolved." It's not based on acoustics, but on subjective and "functional" contexts.
    The attempt of this thread to make a "theory" out of "tendencies" of seventh chords clearly places itself in the camp of those who feel that 'dissonances' must be 'resolved' because of their 'tendencies.'
    Diminished chords simply reveal the glitches in the diatonic system, in which root movement by fifths (interval of 7, not a multiple of 12 until 7x12=84) is never far away from the tritone (6+6, 2+2+2+2+2+2, 3x4 = 12).
    Fifths encourage travel, tritones are static localized nodes of travel. Thus, root movement is the point, not resolution of dissonance.
    This is probably the strongest case for the 'tendencies' argument, since it is based most closely on the fifth, which acoustically is the most consonant interval after 1:1 (unison) and 2:1 (octave). The rest are questionable.
    Acoustic ratios are the only approach which considers sound itself (intervals) as its context. The other 'theories' are based on 'artistic' considerations, which often have little to do with actual sound.
    Last edited by millionrainbows; Jan-10-2020 at 21:31.

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    Most dissonant intervals to most consonant intervals, within one octave:
    1. minor seventh (C-Bb) 9:16
    2. major seventh (C-B) 8:15
    3. major second (C-D) 8:9
    4. minor sixth (C-Ab) 5:8
    5. minor third (C-Eb) 5:6
    6. major third (C-E) 4:5
    7. major sixth (C-A) 3:5
    8. perfect fourth (C-F) 3:4
    9. perfect fifth (C-G) 2:3
    10. octave (C-C') 1:2
    11. unison (C-C) 1:1

    The steps of our tonal scales, and the "functions" of the chords built thereon, are the direct result of interval ratios, all in relation to a "keynote" or unity of 1; the intervals not only have a dissonant/consonant quality determined by their ratio, but also are given a specific scale degree (function) and place in relation to "1" or the Tonic. This is where all "linear function" originated, and is still manifest as ratios (intervals), which are at the same time, physical harmonic phenomena.

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    Senior Member SONNET CLV's Avatar
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    I wish I understood all this theory about seventh chords. But I don't. I'll have to remain content to just listen to "Waltz for Debby" by Bill Evans.

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    Senior Member Woodduck's Avatar
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    Quote Originally Posted by SONNET CLV View Post
    I wish I understood all this theory about seventh chords. But I don't. I'll have to remain content to just listen to "Waltz for Debby" by Bill Evans.
    Just by the way, most of "Waltz for Debbie" is in duple time. For that matter, so is "Waltzing Matilda."

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    Isnt the word "tendency" just another way of describing the same idea that in classical tonal music 7ths tend to want to resolve in a particular way. This is taught in universities, you're just using different terminology.

    In any case, the idea of 7ths needing to resolve only applies to certain musical context as others have pointed out as irs partly a psychological phenomenon. It's possible and very common now to wtite music with lots of chords traditionally labelled as dissonant that don't sound dissonant due to aesthetic and musical reasons. We only hear dissonance in music that sets up harmonic consonance to create stability so that then dissonance can be used to create tension and therefore musical interest. Musical interest and contrast can be achieved in other ways than tonal harmony such as syncopation, ear work bass lines, repetition etc. With that type of music harmonic dissonance is often not relevant.

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    The way the OP question is framed confuses CP theory with acoustic notions of dissonance.

    If you want unresolved dom7s, go to jazz or blues. But nobody in either system is thinking literally or primarily in terms of acoustic dissonance or consonance.
    Last edited by millionrainbows; Mar-19-2020 at 14:03.

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