Every brass player has heard of the idea how important long tone practice is, and how the old time players relied it. My question is; what kind of long tones are we talking about? The kind where you take a breath and squeeze out a note to save air for later on? Just playing a long tone doesn’t do anything unless it’s the right kind. What’s the right kind? Think of a large beach ball filled to maximum capacity. If the plug is removed the air escapes in a sudden rush because of the pressure inside and the elasticity of the ball. The ball is made of a material that will easily expand when filled. It is not necessary for the outside of the ball to be contracted by squeezing it. The elasticity and the pressure inside is more than enough to expel the air in a steady, even manner. That’s the same idea a brass player needs to produce a long tone. The lungs are filled to capacity, the embouchure seals at the moment of exit, the tongue recedes and the pressure behind the embouchure propels the air forward passed the lips, causing them to vibrate as it passes. No other action is required from the rest of the body. Just as the ball needed no squeeze from the outside to release the air, the embouchure needs no push from the torso to release the air.
The best way to practice long tones, and by best I mean produce the most beautiful sound, is to begin each note with a bell-like start in order to relax as quickly as possible. The bell-like shape of the note will start the air fast enough where no pushing is necessary from the body. The relaxation after the start of the note will allow for maximum resonance. In a sense the torso becomes the concert hall: if the diaphragm muscles are engaged and tight, the concert hall will sound small and dead. If the diaphragm muscles are relaxed the concert hall will sound spacious and reverberant.
Long tones should be practiced at all dynamics, starting with a forte dynamic and always diminuendoing in a long steady manner as the lungs naturally empty without any attempt to push air out. In my experience everyone starts the air in too slow a manner to be able to relax quickly enough to get the best sound. You should feel like you are spitting the air a long distance. Then the only other action required is keeping the embouchure perfectly still by having a perfect seal against the mouthpiece. This way all physical action is accomplished from the chin up, which is the only way to get optimum resonance. Your only responsibility once the air is instantly dispatched is to make sure the air is released in an even manner from the lungs naturally deflating without an ounce of pushing from the body. This will result in a long even diminuendo and the best sound you can produce. When a sustained dynamic is called for this is accomplished by the muscles of the rib cage and not the diaphragm. Long tones should be practiced by the method described above with no sustained dynamic, because the sound will be of superior quality and that is the aim of long tone practice, and not simply to hold notes steady. That quality of sound will hopefully be the model later for all types of note shapes.
Now for the most important thing I can impart to you in this article. Everyone can move air fast when playing the louder dynamics, (although most people even then don’t move it fast enough) but as soon as the dynamic is reduced the air will automatically slow down, causing the sound to change, lose focus and projection. The way to think about the sound in the softer dynamics is to imagine a forte dynamic that has been moved a distance away. In other words it is the same sound, same clarity, same intensity and focus, just farther away. The only way to achieve this is to not slow down the air stream when playing soft. Less air will be used at the softer dynamics but it must move at the same speed to get the same sound as in the louder dynamics. This can be done by narrowing the aperture of the embouchure so that the air stream is concentrated into a smaller area causing it to move faster. Think of long tones as ringing a big bell and then a small bell. The small bell never rings slower; in fact it appears to ring quicker, and that’s the feeling we need to keep in mind when changing dynamics from loud to soft.