by Kirk Lundbeck

According to Wikipedia, PSI or pound per square inch or, more accurately, pound-force per square inch (symbol: psi or lbf/in² or lbf/in²) is a unit of pressure or of stress based on avoirdupois units. Or more simply it is the pressure resulting from a force of one pound-force applied to an area of one square inch. As trombonists we serve as the air compressor for our instrument. The problem lies in the fact that most of us use an insufficient amount of air for the sound we are trying to produce especially in the high register. In the upper register instead using proper air stream flow we tighten our muscles, move our slide too fast and press the mouthpiece against our lips with a force strong enough to crack the enamel on our teeth or even worse using a big embouchure shift to squeak out those notes in the stratosphere. Here’s a way that I’ve been using with my students and even on myself and it has made a significant difference in my range, both high and low.

This concept stems from a recent article on this website from my dear friend and mentor, Jay Friedman called “Up Yours.” In this article he writes about how for years he has taught his students, including yours truly to “aim the air stream straight through the throat of the mouthpiece,” bypassing the cup altogether. He feels that this isn’t even enough to focus the air stream to create the “core” sound. Now he tells his students to, “aim their air right below the upper rim of the mouthpiece, which requires more support from the corners of the embouchure and results in a much better, livelier sound.” I totally agree this definitely works. But there’s still more. Focusing the air stream right below the upper rim of the mouthpiece works beautifully if the “APSI” is right. “APSI” is according to yours truly is Air Pressure Stream Intensity. This intensity can be demonstrated by blowing through air a straw and holding a piece of paper against a wall. The farther you move the straw away from the wall the harder it is to hold up the paper. Try it without the straw and you have to really focus the air coming from your lips to hold the paper up at all and not for very long. The air coming from our lips isn’t as focused as it is from the straw. If an air compressor is filled with 200psi of air and a 2 inch diameter hose is attached the air escapes from holding tank rather quickly. But attach an 1/8 of an inch hose and the same amount of air takes much longer and comes out with more intensity. I tell my students to think of this when trying to increase their range on both ends of their horn. In order to play higher the air capacity is the same but the air hose is smaller so the flow is more intense. Aim for the upper rim of the mouthpiece as Jay says and reduce the size of the “hose” that’s shoots the air into the mouthpiece. In the same way increase the size of the hose to play lower still keeping the air stream aimed towards the upper rim of the mouthpiece. Due this simple exercise. Start on middle Bb, slur to the Eb above and slur to the G above and back down as slow as you can in one breath. Then B natural to E natural to Ab. C to F to A natural and so on. On each slur higher increase the intensity of the air stream by thinking of the “hose” between your lips getting smaller, but not restricted thus making those high register notes pop right out of your horn with no increased mouthpiece pressure against your lips. As you work the lower register do the same type of slurring exercise but as you go lower think of the “hose” increasing in size. The lower notes come out clear and strong.

— Kirk Lundbeck

I want to add a thought to Kirk’s excellent article. When playing a passage in the middle-low register, if you want a tenor-bass sound rather than a strictly tenor sound, move the mouthpiece up slightly as if you were going to play a pedal tone. This gives a much rounder, darker sound than a normal setting. However, even with this setting it is very important to still try to have the air stream emerge from the embouchure at a relatively high angle to give clarity and resonance to the sound, and keep the pitch and timbre from dropping, a common occurrence.

Jay Friedman