In jazz, it seems, it can't be jazz unless the 7th of the chord is smashed in there somewhere. The more I study, the more I see the 7th (major or the dominant) stuck in a voicing.
I suppose it makes sense to a certain degree. The obscurity of of jazz calls for distinct sound. The seventh lends itself to not only jazz but rock, soul, gospel, and even some classical. It's just another piece of the musical puzzle. An interesting flavor to put in when we need more umph to pieces. A flair if you will.
But how much more interesting is the 9th! or the 11th? The 13th shows up once in a while. At first, these things baffled me. If a scale has only 8 notes (C scale: C - D - E - F - G - A - B - and C again) then how can we have a 9th or a 13th? The 7th and 6th make sense, but what the heck is this stuff?
If a chord in it's basic structure is the 1st (tonic), the 3rd, and the 5th, then what's going on? Well, here it is in a nutshell. The 9th is just the 2nd an octave up. The 11th is the 4th an octave up. The 13th is the 6th... You guessed it, an octave up.
Why write chords this way? Why not just write the 4th or the 6th? (ex: Gsus4 or G6) I guess, it's the octave. They want you to space apart your voicing.
When voicings are too close together it doesn't always sound very pleasant. It can be a jumbled mess! But Oh! The magic that can happen when we space out our notes! It can be the difference between grade school painting and a Master's brushstrokes.
Try it the next time you want to play a chord. You'll hear the difference.
Keep learning!
