Update 4/15/06: For better examples of note limiting, please check out my LEARNING TO IMPROVISE: RHYTHM article.
iwasdoingallright - audio clip - note limiting clip.
I'm playing a solo to an Aebersold recording of Jordu. As you listen, you may notice that I'm NOT playing a wide variety of notes. In fact, I'm just playing four notes (in varying octaves) throughout the solo: D, F, A, Ab.
I have a few improvisation exercises that I do from time to time. This one, I call "Note Limiting." It works particularly well with blues-based chord progressions. The concept is simple: pick a few notes and play ONLY those notes during your improvised solo.
This exercise has the following benefits:
Since we're only dealing with a few notes throughout the solo, you don't have to worry about which notes to play over which chords. This is especially helpful to beginning improvisers who may stumble through chord progressions. Once you pick your notes (I'm using 1, 3, 5, and 5b in this clip - iwasdoingallright - audio clip), the focus shifts from theory, to creating music.
ENHANCES RHYTHMIC DEVELOPMENT
Even though I talk a lot about ear training on this site, the fact remains: it don't mean a thing if it ain't got that swing. Interesting and well-phrased rhythms are crucial to a good sounding solo. I find that beginning players (and experienced players too!) often get so caught up with notes that they don't even think about rhythms. That's the beauty of this exercise: you can't get hung up on notes. Try to play one or two notes, and make them sound cool. Rhythm is your key. I suggest short punchy rhythms.
I'm not a great improviser. Sometimes I feel like I'm in a rut. Either I can't think of anything cool to play, or I think I'm playing the same licks over and over again. When these issues arise, I turn to an exercise like this. It creates a natural change in my playing. It basically forces me to think differently about my solos. Typically, after a few "Note Limiting" exercises, I approach regular improvisation with renewed excitement and creativity.