Every once in a while I come across a book or internet resource that talks about an off-center aperture, usually in the context of explaining why some players have a mouthpiece placement to one side or another. The general idea of many is that if a player’s free buzzing embouchure has an aperture that is to one side then this player should place the mouthpiece in such a way that the aperture gets centered inside the mouthpiece. On the surface this seems logical, but like many seemingly convincing descriptions of brass embouchures, it is too simplistic an explanation and doesn’t conform to what you will see if you take a closer look.
First, I should explain exactly what the aperture is, since some people may not know or have an inaccurate understanding. The brass embouchure aperture is the opening that blown apart by the air and then closed by the combination of the muscular contraction of the lips and, less so, by the equalization of air pressure. Some players imagine the aperture as an open hole or having a particular shape or size, but it’s really constantly changing. Lloyd Leno filmed trombonists playing with a transparent mouthpiece with high speed photography to look closely at the lip vibrations and you can see the apertures in his video (the complete video in three parts can be viewed at the link).
Returning to the topic of an off-center aperture, one thing that you will notice if you look closely at all the players in Leno’s film closely is that many of them have apertures that are slightly off center inside the mouthpiece. That is, the center of the aperture doesn’t necessarily align with the center of the mouthpiece. Leno comments on this a couple of times the the entire film. In the clip I’ve embedded above you can see one very easy to spot off-center aperture beginning around 46 seconds into the video.
Before I go any further I should point out that by “off-center” I’m referring to the horizontal plane, not how high or low the lips are placed inside the mouthpiece. The ratio of upper to lower lip inside the mouthpiece is an important feature of a brass player’s embouchure, but is gets into other topics that I’ve addressed elsewhere.
My own aperture is off-center inside the mouthpiece.
In this photo I’m playing a low B flat on trombone (the B flat an octave and a second below middle C on the piano). I took a photo of me buzzing on a rim visualizer which has an even clearer view of the aperture being formed off-center of the rim. Because the rim visualizer doesn’t provide the same situation as actually playing an instrument, we should take rim buzzing with a grain of salt. It’s probably not as accurate a depiction as with a transparent mouthpiece.
Other brass players have also noted that apertures are not always centered inside the mouthpiece while playing. Horn blogger John Ericson pointed out his off-center aperture here. Looking through the photographs I took of trombone players’ embouchures for my dissertation and glancing through the video footage I’ve taken of brass players on all instruments show a number of other players who have an aperture that isn’t centered in their lips, as well as many who do have a centered aperture. There really wasn’t a correlation between an off-centered aperture and playing ability, however.
In my own case, my aperture forms slightly to the left of center (from the photographs point of view, on the right of my lips), even though I place the mouthpiece slightly to the opposite side. I won’t speak for everyone else with similar embouchure features, but this mouthpiece placement was chosen with some conscious thought because this is the spot on my lips where my embouchure functions most efficiently. Trying to move the placement to line up the aperture centered simply doesn’t work as well.
However, this is not where the aperture forms when I free buzz. It’s a little hard to tell because I wasn’t able to capture the aperture at a very open position with the low resolution camera I happened to be using here, but my free buzzing aperture actually forms more on the right of the camera’s point of view (left side of my lips). The addition of the mouthpiece (or rim alone) is enough to alter my embouchure so that the aperture forms at a different spot on the lips.
Other players may get different results. With many players the free buzzing aperture and playing aperture can be observed to be in about the same spot. Others may get even more radical differences than me. I think this challenges the idea that the aperture must be centered inside the mouthpiece. Even more so, the idea that free buzzing informs where the mouthpiece should be placed should be questioned. In my opinion, free buzzing is a poor diagnostic tool for looking at the embouchure. If someone tells you to change your embouchure based on watching you free buzz or because they feel the aperture should be centered inside the mouthpiece, I think it’s fair to treat their advice with some healthy skepticism.