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One particular jazz piano technique is to voice chords using quartal voicings. A quartal voicing is a chord built on fourths. For example, one might voice Cmin with the notes (in ascending order) F-B♭-E♭. Iconic examples of this technique can be found in Chick Corea's album Now He Sings, Now He Sobs.

Jazz pianists often use this technique to "go out." That is, they often use quartal voicings to depart from the written chords/harmonies. However, quartal voicings are ambiguous. For instance, the chord above (F-B♭-E♭) could also be a voicing for E♭Maj, E♭min, B♭sus, G7♯9, D♭Maj, D♭7, etc.

So, in these contexts, how are quartal voicings used to "go out" when improvising?

Typically you choose the quartal voicing after you have decided on what mode to improvise with. For example, if the chord is Cm, you are likely to choose the dorian mode. Then you have many choices for quartal voicings that are enharmonic to that mode. The example you've given, F-Bb-Eb, is widely used over Cm because it includes both the 3rd and the 7th, but there are many (seven) quartal voicings of this shape that come from C dorian:

• C-F-Bb




• D-G-C




• Eb-A-D




• F-Bb-Eb




• G-C-F




• A-D-G




• Bb-Eb-A

(You might note that these are exactly the same as the voicings you get in Eb lydian or F mixolydian, which are equivalent modes to C dorian. But since the chord symbol was Cm, we know the bass note is C, so strictly speaking we should refer to this mode as C dorian.)

Practice making the quartal "claw" with your left hand and moving up and down the dorian mode enharmonically in this manner. If you play around with these voicings, you will notice that some feel especially dissonant, others somewhat hollow. That variance is what makes quartal comping interesting. As you comp, you can create little countermelodies by choosing voicings that match (or contrast) with what you're doing in your right hand.

This approach is discussed in detail in Mark Levine, The Jazz Piano Book.

Your question is about what notes you can use in your right hand, but I hope my answer makes it clear that the right hand and left hand are actually following a similar thought process when you use this approach to improvising. First, you look at the chord and choose a suitable mode. Then, you combine left hand voicings and right hand melodies to your liking according to that mode.

As for "going out," this term usually refers to when we break from the expected mode and play notes that normally "don't work." Quartal voicings (especially those that consist of perfect fourths only) are useful when playing out because they have such a symmetrical, strong structure. They sound OK even if you choose a quartal voicing with an arbitrary relationship to the tonic.

For example, after playing in C dorian over a Cm chord for a while, you may choose to create tension by playing in C# dorian for a phrase and then resolving back down. Your left hand voicing could move in parallel from F-Bb-Eb to F#-B-E for a moment, with the right hand following suit by playing melodies from the C# dorian scale, then you would resolve back on a C dorian voicing. It takes a lot of practice to learn to do this tastefully, of course, but Chick Corea makes for an excellent reference.