The concept is very simple (concepts are very simple and obvious in theory but difficult to practice) :
- You can play (or compose) every note you want if it sounds good
You can play or compose nay notes you want, the important thing is “sounding” well.
- Absolute “wrong” notes do not exist. A wrong note is when a tension (not chordal note) is not resolved!
Absolute wrong notes do not exist, that is a note, which does not combine with any chord, does not exist: a note becomes wrong, that is it does not “sound good”, if it is a NOT solved tension or dissonance.
- Sometimes you can break the rules and play “wrong” notes, if they sound good. But BE CAREFUL with this dangerous sounds.
You can sometimes violate rules and play “wrong” notes if they sound good in jazz improvisation and in a musical composition. However, pay attention to these “dangerous” notes for ears and for chordal and tonal barycentre.
Concepts of psychoacoustic music theory
Important Note: For many (above all jazz) musicians some or also all the marked X are not mistakes. For the American School, for example, the sixth note of major chord is not considered a dissonance. I do not agree to it, may be because I have done classical studies (note that G on BbMaj7 is marked as a mistake).
A mistake that is a wrong note can be a cue from which new ideas start. For example, if a pianist plays a note without an harmonic meaning compared to the chord, can begin to repeat that wrong note more times and then resolve on a chordal note to rest that tension. Persisting by smartness on that note, you let the listener understand it and insert it in the music. It is a so-called trick of acoustic psychology.
In everyday life too, as a wrong or strange sentence is emphasized by purpose, it is pleasantly accepted by the interlocutor so every sound can make-sense when you play, also if you have to follow harmony and music theory.
Free resources on jazz improvisation and music theory
In music there are not right notes or wrong notes: there are tension not solved or too much dissonances. Good music is a balance between tension and rest. Music theory and harmony is a way to understand the meaning of music, if you know them you can play and compose very easily. According to music theory and harmony, melody is a balance between tensions and resolutions, dissonances and consonances, energy and rest. Melody lines must be harmonic, symmetric, and balanced.