Blocked buzzing is a bit of an unorthodox tool that I use in rehabilitation and a technique which is discussed in all of my books. In rehabilitation, blocked buzzing is utilized exclusively as an analytical tool; however, it can also be used as a warm up, to get into shape, or to stay in shape while on vacation. This is how to block buzz:
Close the end of your mouthpiece completely with a finger. Put your mouthpiece up to your lips exactly as though you were going to buzz a midrange note. Begin blowing by tonguing the note. Blow with a constant mezzo forte stream of air. (There should be absolutely no sound or air leakage from your lips or mouthpiece. You are just blowing silently against the resistance.) Notice how firm and controlled your entire embouchure is and how your chin stretches down with considerable energy as you blow. Tongue a few notes with your mouthpiece blocked, and observe how still your face and throat are and how well your air works.
If you are having embouchure and playing issues, the structure your face generates to block buzz is how your embouchure functioned prior to the onset of your problem. Embouchures that have developed overuse-related dysfunction deprogram themselves to set with this degree muscle energy and control. In blocked buzzing, even the most dysfunctional of embouchures configures mechanically correctly, and an injured player does not feel mouthpiece pressure, lip pain, or the degree of facial fatigue that he experiences in playing.
Let’s do that again. Block buzz in slow motion, and pay close attention to how your embouchure physically prepares and sets itself. Without thought, your facial muscles automatically configure to blow against the resistance with an intense, balanced, controlled structure. The normal level of embouchure stability generated by a healthy embouchure in playing is comparable to that generated naturally by the embouchure for blocked buzzing.