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This seems counterintuitive, since they are simply displaced by an octave. There must be some kind of acoustical phenomenon that explains it, in terms of the difference between the frequencies.
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11-19-2018 05:39 PM
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I’m not certain, but my physics-based hunch goes something like this:
For sake of simplicity, assume you have two signals that are pure sine waves. If you sum them in the human ear, it will be perceived as both the original signals plus two more sine waves at “beat frequencies” that are the sum and difference between the two original frequencies. The sum and difference signals are usually lower amplitude than the original signals, but can certainly be audible. When the two original frequencies are far apart (like a minor 9th) they are generally not noticed. But when the original sine waves are close in frequency (like a minor 2nd) the difference frequency can be heard and can sound unmusical since it generally is out of key. Of course, this beating phenomenon is very useful when we tune.
Beat (acoustics) - Wikipedia
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Yes, I'd thought of the "beat" aspect but it seems that since the beats are more audible with the minor 2nd, so that would be the one sounding more dissonant, though it's the opposite.
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The minor ninth and minor second are the same pitch class, but don't sound the "same" harmonically.
This is why I think of scales as needing to be comprised of two octaves in order to capture everything. The chord tones live in the lower octave, the extensions live in the upper octave.
This can be a little misleading on the guitar because almost all the usual stock 6 and 5 string major and minor chords have just ones and fives in the lower octave and the chord tones in the upper octave. This helps playing the guitar unaccompanied where the extra octave below fills in for the missing bass player, but those chords can sometimes position the chord tones over the lower octave in such a way to make them sound more like extensions, and confuse you as to whether a note is supposed to be a second or a ninth, etc... (because it depends which octave you think of as the chord tone octave, the "empty" one below or the full one above).
Once you play with a bassist and drop the guitar's redundant lower octave and play the "upper" remaining octave as either the "true" chord tone octave (triads) or treat it as a rootless extension octave (fancy), then it gets clearer which notes are doing what.
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min 9 more dissonant than min 2?
Says who?
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This seems counterintuitive, since they are simply displaced by an octave. There must be some kind of acoustical phenomenon that explains it, in terms of the difference between the frequencies.
It all depends on contexts, man...
Even if there is no context - if you hear something more or less dissonant that means we subconciously apply some context to it.
Acoustics has alsmot nothing to do with that... it describes sounds physically.
Consonance and dissonance are musical notions, and music is absolutely cultural thing.
It is like colours - physics can describe it, biology can describe how eye sees it and all..
but the blue seems to be peaceful colour to many in our culture and at the same time it is dangerous in another culture.... it is nothing about physical or biological thing.
So try to figure out the context you hear it in..
In my opinion supposedly minor 2 to modern ear of a musician involved in modern music can sound more like a 'single sound', colouristic cluster, dissonant extra harmonic... and minor9th is too diatant for that.. thatnk to distanst you can hear it better so it tends to resolve more...
But it is one of the possible ideas aas I do not really know how you hear it.
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Originally Posted by Vladan
Min 2 has a bit more 'rub' if you play it next to the minor 3rd like Bill Evans did. But I don't hear it as particularly dissonant, more 'moody/atmospheric'.
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Um, you sure you haven't got that backwards?
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Originally Posted by grahambop
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Ok I assumed OP meant chords.
If it’s intervals I’m not sure which one sounds worse!
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Originally Posted by ll00l0l
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Sometimes, for a Cm7, I play xx574x. Just xxx74x would work. m2 interval. Dissonant, sure, but musical in that situation.
But, I don't think that x5xx4x sounds as good against Cm7.
minor intervals occur in b9 chords of course. I've never thought to just play the two notes a m9 apart.
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Originally Posted by rpjazzguitar
C7b9: x3232x
G7b9: xx5464
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Maybe I'm misunderstanding something, but a m9 chord has a M2 (major 2nd) interval as the 9th. A-C-E-G-B (the A to B is a major 2nd). So, a minor 2nd is not the same interval. mb9 chord (A-C-E-G-Bb) would be the same apples to apples comparison. No?
Also, when you spread a chord out you tend to get less dissonance. So if you play a A against a Bb in the same registry, it's more dissonant than A against a Bb that's an octave higher. Or, at least that's how we perceive it... I think the bleating or dissonant pulsing between the notes would be the same on a graph, but at that higher pitch we don't hear them as well. Also, depending if you invert the chord, you could make it less dissonant due to the newfound interacting interval structures in the inversions.
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Originally Posted by BigDaddyLoveHandles
For example, I sometimes play xxx74x for Cm7. D and Eb.
But, I have never thought to play, say, x5xx4x. (Or similar up an octave).
And, for that matter, it never occurred to me to suggest C7b9 by playing x3xx2x. But, in that case, it doesn't occur to me to play two notes a half step apart anyway. It doesn't seem like playing a C and a Db (only) a half step apart really gets to the quality of the chord.
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Originally Posted by Vladan
Again, it's context and its all subjective... if you just take that same m2 of B and C a half-step apart and play it without the surrounding notes, it may indeed sound more dissonant... or not, perhaps depending on how you play it.
Similarly, I find the m9 in a dom7b9 chord to be interesting not unpleasant . Pretty much any of the conventional jazz guitar voicings for dom7b9 chords demonstrate this (to my ear, at least).
Without the surrounding notes, I will grant you that the m9 interval does sound less dissonant to me than the bare m2... and I'll leave the reasons why to the acousticians, physicists and mathematicians on this thread. As the joke goes, I can only count to four (five or 7 in a pinch!)
SJ
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Originally Posted by rpjazzguitar
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Think of this also: generally minor 9th intervals are avoided in chord voicings except for 7b9's. For example, the aforementioned CMaj7 chord voiced (from the bottom) G B C E would not normally be voiced B/E/G/C due to the minor 9th. In contrast, minor 2nd's are used much more liberally, as in the first voicing.
This says to me that the m9 is heard as more dissonant in practice, even if we can't acoustically determine a reason.
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Originally Posted by rpjazzguitar
I think this is because of what I mentioned in post #4... your close notes are be being heard in context as upper octave extensions?
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An example of this:
Cmaj7 played as xx9988. Easy to play. Has the root on top. But, doesn't sound very good unless you can find a very congenial application.
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Originally Posted by rpjazzguitar
B E G C
B G is "first inversionish" of G
E C is "first inversionish" of C
Both source and destination of the cadence sound together and irritate the mind's ear.
That voicing functioning as maj7 has a similar roughness heard in loose quartal chords (that roughness is often dissipated by the quartal chords subbing for maj7, rooted a major third above, smoothing out nicely when played in various contexts)... Ebmaj7 replaced by G7#9sus4 kind of sound.
The quirky V->I combo-cadence feel mentioned above can be broken directly by chromatic movement. For example, in the beginning of Green Dolphin Street, the chromatic maj7 moves are often "unsweetened" by replacing them with quartal chords as above, which is a clue as to how to use this difficult but similarly sounding 7351 voicing... used as a little bit different kind of edge that can sound quite right for a chromatic vamp in with the melody line is just the chords' roots (melodic tonic harmonic chromatic parallelism - OMG what could be more boring?) but for an unusual voicing with an edge (like this one that tops the root).
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One notable exception to the root-on-top Maj7 voicing as above, is when it's the 7th in the bass moving down from the root, like in a kind of "march" ostinato (bass: root, 7, 6, 5) over major chord. That doesn't sound as dissonant, possibly because of the wider separation between the body of the chord and the bass way below.
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IMO, the reason that voicing sound dissonant to some people is in equal temperament. Adjust one, or two of those notes for couple of cents and voila, as sweet as it can be.
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How would you adjust it exactly?
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I would not, but if I would, I would bend strings, untill it sounded good.
Godin 5th Avenue Kingpin comparisons
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