The embouchure “aperture” is defined as the hole in which air passes through as the brass musician plays the instruments, but there is a degree of controversy over what the aperture is doing while sustaining a pitch. More specifically, a number of players and teachers claim that the aperture is always open while blowing. Here are just a few.

Technically, the aperture is always open while playing, otherwise air would not be moving through the lips. For our intents, think of the size of the aperture as being on a sliding scale that oscillates  between varying degrees of openness and closedness.

Open vs Closed Aperture

For years we have been told that our lips are supposed to be buzzing at all times when we play any notes. In fact, the lips must vibrate but NOT in the close configurations as when we do lip buzzing.

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We need to tighten our lips in order to play, but the lips themselves should always be squeezing against a lovely cushion of air, not squeezing against each other.

. . .

The smaller a gap is the quicker the air has to travel to get through it, but there must always be a gap.

The Aperture

As air is forced through the lips, the lips never touch each other. Instead, they oscillate because of the shifts in air pressure, turbulent eddies in the mouthpiece and elasticity of the skin.

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Similarly, the aperture must remain open and oval in shape.

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To add to the confusion, many teachers and players also describe the embouchure aperture as needing to be “open” or “closed,” but appear to be talking about the general size or shape of the aperture overall, rather than keeping the lips completely in an open position while playing. I’ve also read some players describe an “open” aperture as one where the player begins the pitch with the lips in an open position and a “closed” aperture where the lips are touching and the aperture is blown apart to start.

The trouble with all the above is that it is speculation, largely based on playing sensations. Since a great deal of brass playing happens inside the mouthpiece at high speed, where we really can’t easily see what’s going on, we’re going to inherently rely on what we think is happening. However, there have been several observational studies which clearly show the brass embouchure functioning, so we don’t need to speculate. Look at the following videos and see whether the embouchure aperture remains open.

It’s quite clear from all this video footage that the embouchure aperture opens and closes rapidly during the production of a tone on a brass instrument. Further details show that the higher the pitch the smaller overall the aperture gets at it’s largest spot while lower notes have a larger opening at the most open end of the cycle. Likewise, louder notes end up with the aperture cycle being larger and softer notes have a smaller cycle. In spite of what the earlier players and teachers claim, it really doesn’t appear that brass musicians play with their aperture open at all times.

Why is this important? Well for one, I find it interesting and think describing the actual function of brass playing correctly to be more honest. There’s really nothing wrong with teaching and practicing with analogy or inaccurate playing sensations leading our technique – so long as those are understood to be analogies. But playing sensations are different from player to player. Leading a student to efficient playing technique may be effective by asking her to play with an “open aperture,” but if the student is too loose in the first place then this advice could lead to the a more extreme problem. Even if the analogy initially works, mistaking it for truth can lead to the student continuing to move towards that analogy and take it too far in the long term.

Facts do matter. If you’re going to teach by analogy just make a quick point to clarify that this is just “how you like to feel or think of it.” Teach the truth.