Jazz improvisation, which is basically making and playing a little composition in real time, is a creative act coming from the performer’s personal storehouse of ideas and techniques. Students often remark that they just can’t think of anything to play. Two concepts that are crucial to this ability can be termed as “playing by ear” and “playing by eye.”
First, playing by ear. If you can’t read music at all, or can’t see at all, playing by ear is all you have got. And, if you are sufficiently gifted, it can be all you need. Playing by ear involves trained listening, then storing of sounds and patterns, then the ability to perform based on those stored sounds and patterns. Tone, tuning, vibrato, style and many other nuances of performance are rooted in hearing. Music lives in the realm of hearing. The more you listen and take in – the better player you can be – up to a point.
For most of us moderately gifted mortals, the playing by eye part can help greatly in achieving a higher level of jazz skills. Of course, first in the line of eye skills is proficiency in reading musical notation. But then in addition to the notes, what about all those colorful jazz chords we see symbolized on the music sheet. How can you know what tones will fit well in the harmony you are about to improvise on. That is when the playing by eye skills really kick in. Chords and scales are like letters in the alphabet that are used to make words in a story. Today’s jazz theory teaches a correlation between chords and scales, or in other words, when you see or play a C major chord, the improvisor learns that the appropriate scale would probably be C major. I say probably, because it could also be C lydian, which is the 8-note scale built on the forth note of the G major scale. Taking this much further, the many possible chords in jazz (or any music genre) harmony can be correlated with various scales and modes to serve as resources for improvisation. This gets complicated. This is why we go to music school and read technical books and spend lots of time and effort learning stuff.
Ironically, the best “by eye” players are able to hear in their mind what they see on the paper. One of my lab band instructors at University of North Texas asked the band during rehearsal one day to “show me the music.” We all held up the part we were reading. He then said, “No, that is the paper, not the music.” The trick is to turn the notes and info on the paper into a musical performance. That means transforming what you see into what everyone hears. This skill can also be applied to play improvised melodies and patterns based on internalized knowledge of the notes and sounds of chords and scales. Now we are getting into advanced performance territory.
The skills and knowledge of playing by ear and by eye end up working together in a synergistic way. This can also be explained as a coordinated left brain plus right brain thought process. Left brain analytical/methodical plus right brain creative/sensory equals best artistic outcome. So if you really want to be a great jazz improvisor, listen to lots of good jazz, internalize the sounds, study jazz theory, then add that knowledge to your internalized sound bank. Then when your solo comes up and you look at the lead sheet with melody notes and chord symbols you can hear in your mind what it might sound like before and while you are playing that great solo.