extended chords - why is 3-11 dissonnance avoided but not 7(dom)-13?

[-nara-]

ciao piano street people, this is my first post (so hello to all)

i'm working dan hearle's the jazz language (which i think is generally superb for me, i learned guitar by ear so have basic musicality, but little book theory, and this book is super accessible from that starting point) and i have become stuck on an aspect of extended chords which is annoying me (i've tried websearches but to no avail).

basically i understand that the major 7th and dominant 7th chords have a major third that is only a semitone apart from the 11th, which means the 11th is either raised od the 3rd dropped to avoid that semitone dissonace (if one wants to avoid it). so far so good.

but nothing is said about the semitone dissonace that arises between the dominant 7th (for example Bb in C scale) and the 6th of the same scale (for example A in C scale).

why is one dissonance avoided but the other not (as far as i can find) addressed?

btw i'm a learner, so i would be grateful if any answers and suggestions were not too jargon heavy.

thank you for any ideas and suggestions in advance

[-nara-]

*didn't express this bit as clearly as i could have

"but nothing is said about the semitone dissonace that arises between the dominant 7th (for example Bb in C scale) and the 6th of the same scale (for example A in C scale)."

by 6th i really mean the 13th (which is the same note as the 6th just an octave higher). i just remember it as a 6th (sorry if that confused anyone).

[vandoren]

Hi nara,

The explanation that I've seen in various places is that a natural 11th as an extension in a major (or dominant) chord in combination with the 3rd of the chord leads to an interval of a minor 9th in the voicing.  The minor 9th dissonance is somewhat intense and in many situations it is avoided.  (Though there are certainly exceptions, notably the flat 9th voiced above the root as part of an extended dominant 7th chord.)

To elaborate, let's consider two notes a semi-tone apart, say A and Bb.  We can arrive at different intervals by displacing one of the notes by an octave when we voice them.

1.  a minor second.  (Play the A and Bb right next to each other on the piano).
2.  a major seventh.  (Move the A up an octave so that you are playing Bb below A.)
3.  a minor 9th.  (Move the Bb up an octave so that you are playing A below Bb with an octave in between.)

Although all three of the intervals consist of A and Bb, they have different characters and the dissonance they produce is perceived differently by the listener.  Out of the three, the one that is sometimes considered "too dissonant" and to be sometimes avoided (even in a lot of jazz voicings) is the interval of a minor 9th.  (An octave + a half step.)  Actual minor 2nds ("semitones as you call them") or major 7ths  are fine and occur in many, many beautiful chord voicings.

So, in your question about "why it is OK to voice the 13th in a C dominant chord", the reason is that in typical voicings for C7 with a 13th added the 7th of the chord (Bb) would not be voiced an octave above the 13th (A).  So, the interval formed by these two pitches in typical voicings of C13 would be either a major 7th or a minor 2nd, and would not usually be a minor 9th. 

BTW:  It is common for the A and Bb to be voiced right next to each other (as a minor 2nd) in such a chord.  E.g., in rootless ("Bill Evans") voicings you might see   E A Bb D all played by the left hand  as a voicing for a C7 chord adding in the 13th and the 9 as extensions. 

[vandoren]

Couple side remarks.

1.  As explained above, the reason why we don't usually see an 11th in a major or dominant chord is that it would typically be voiced at the interval of a minor 9th above the 3rd of the chord.

Example:  If our chord is a D dominant 7, the third is F# and the 11th would be a G.  Voicing the G as an extension of the chord most naturally leads to the G being an octave above the F# ->  Minor 9th dissonance.

You could try to instead voice the F# and G right next to each other (to have a minor 2nd instead of a minor 9th), but to my ears this completely muddles the chord, and it is not commonly done. 

Another option is to move the F# an octave (or more) above the G (turning the minor 9th into a major 7th).  The result is a Dsus7  with the 3rd voiced like an extension rather than part of the foundation of the chord.  This type of voicing is commonly used by jazz pianists.  Mark Levine's Jazz Piano Book might talk about it.

2.  11th's sound great as extensions in minor 7th chords.  Since the 3rd is minor, the interval between the 3rd and 11th is a major 9th, so the minor 9th dissonance is no longer present.

[-nara-]

Hey Vandoren, a big thank you for the explanation and clarification.

and an apology for my delay in replying. my usb key (with details for this site on) went weird after i tried to use it in a rogue windows machine that tried to treat it as NTFS (i'm ext4 linux), so i had to reset the drivers to get data back (which was a chore)

but now i can get back into the site, i wanted to thank you for a perfect explanation which i now fully understand entirely due to your thoughtul and well set out examples. you're a good teacher (maybe because you are a bona fide music teacher in real life, or maybe you're a teacher by instinct, in which case a career change option is probably there if you want it).

that flipping of intervals above the octave (compound intervals the technical term i've since discovered) is something i hadn't done much of before i encountered this, so fell into the trap of getting  minors and majors mixed when reversing them.
alas i now realise that was mostly self-inflicted, as the first pages of the book i mentioned (Dan Hearle 'The Jazz Language') actually cover that well, including alll the relevant info about intervals above the octave. but (mea culpa) i was a bit arrogant when i started reading it, leading me to quickly skim read that first chapter in the assumption that i already had a decent grasp of what intervals are and how they work, so didn't need to review it in detail.

i was too impatient to get to the bit about all those lovely fat extended chords, a full grasp of which i now realise depended on my knowing my compound intervals forwards, backwards and upside down. so ultimately i sabotaged myself and will try to learn from that in future.
on the same theme i also found some good youtube videos a couple by a channel called 'walk that bass' entitled 'avoid chords' and one by someone called michel plourde 'intervals over an octave' were helpful in getting the basics nailed down.
but ultimately your explanation here was the most helpful of all, as it was tailored to my particular use case. that gave me the key to the door, so i could find my own way from there.

as an aside, i wonder if my struggle with grasping what is academically considered consonant and dissonant in jazz (and beyond) rests partly on my previous listening, because most of my listening when i was younger was to music by bands that were essentially dissonant by design (Joy Division, Siouxsie and the Banshees, etc). so i grew up with an ear that considered dissonant as desirable and to be sought out (and when i began playing guitar, to be recreated).
and to this day i still love and seek out dissonance, although my tastes have broaded extensively as i have matured.

but perhaps that foundation listening experience complicates things for me in theory contexts like this. because when books and videos try to explain concepts to me from the perspective of dissonance as 'undesirable' or 'to be avoided', i do have to somewhat suspend my natural dissonance-loving musical nature and 'get into role' as someone who accepts that conventional precept in order for the accepted logic of explanations to properly sink in. it's an odd situation.

anway, thank you again for your help with my problem and hearty salutations to you from a wintry Serbia!

[vandoren]

Hi nara, if still around on the board.  Thank you for your kind reply!

Your comments about being used to and appreciating dissonance from other musical settings make a lot of sense. 

And, I wanted to add an extra point about this concept of "avoid notes" that many of the jazz theory books mention (like avoiding voicing the 11th in a major or dominant chord because of the minor 9th dissonance).  My extra point is that you should not take this "avoid note" concept too seriously.  Ultimately, whatever sounds good works! 

In fact, I was watching the Brad Mehldau conversation with Rick Beato on YouTube

and at around 13:30 into the video Brad Mehldau explains how he likes to use one of the "avoid" voicing that I had mentioned over the blues as a way to add extra "crunch".  Specifically, he adds the 11th into a Bill Evans dominant 7 left hand voicing directly in between the 3rd and the 5th.  Something like

E F G Bb D      for C7.   (I'm not sure this is the same key he's playing in in the video.)

Some of the jazz theory books even try to give the impression that soloists (or the right hand of the pianist) should avoid sustaining the 11th in a dominant chord as part of the melody of a solo.  This is ridiculous!  Soloists (piano or other instrumentalists) hang out on this tone all the time.  So, especially in melodies, it's best to not pay much attention to this "avoid note" concept.  Happy exploring!