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“The Embouchure Hole”

“The selection of shape and size of embouchure seems to be largely one of individual choice or habit; an embouchure which one performer finds to be excellent another cannot use.” ––Dayton C. Miller 

The geometry of a flute embouchure hole is more complex than it looks because there are many intersecting curves and bevels forming curious three-dimensional shapes. Flute players feel minute differences in each headjoint and prefer one over another. The art and science to create such subtleties are elusive and not easily understood. It all starts at the embouchure hole where the air column first comes into contact with the flute.

There are four basic types of embouchure holes:

Type 1


Type 2

Rounded rectangle, modern or traditional

Type 3

Rectangle with rounded corners, undercut and overcut

Type 4

Wave design



Type 1 (Godfroy)                                                                    Type 2 (Louis Lot)


Type 3 (Haynes)                                                                      Type 4 (Flutemaker’s Guild piccolo)

As a headjoint maker, I have experimented with all four types of design and consider this a reasonable way to describe and categorize a century and a half of embouchure hole development.

The measurements that are crucial to the embouchure hole are the distances from front to back, side to side, and corner to corner (diagonal). Other particulars are as follows: the amount of undercut and overcut, wall angle and wall height, curvature of the lipplate, material used, sharpness of the blowing edge, flatness of the blowing wall, and the general internal shape. Small changes in any of these features will alter the overall characteristics of a headjoint in profound ways.

In his book The Flute and Flute Playing, published in 1871, Theobald Boehm gave the basic formula and measurements of the embouchure: 10 mm x 12 mm, 4.2 mm wall height, 7 degrees wall, and shape of a rectangle with rounded corners (Type 3 with no undercut.). He concluded that “a mouth-hole in shape like an elongated rectangle with rounded corners, presenting a long edge to the wide air stream, will allow more air to be effective than would a round or oval hole of equal size.”

It seems fitting to first address the Type 3 hole because of its popularity today and Boehm’s preference for it. The modern-day Type 3 has much undercutting, a high wall relative to Boehm’s original design, and a narrow lipplate–steeper in the front and pushed in at the back.

In general, undercutting the embouchure will make a headjoint blow more freely. It can be interpreted by the player as having less resistance and sounding louder. The undercutting also compensates for a higher wall since a high wall impedes a free and easy third register. One reason for the current wall height is to give a larger target for the airstream, making the headjoint easy to play, especially in the low register. The narrower lipplate is yet another device in creating a free-blowing headjoint. Some makers even eliminate the entire section of the lipplate in front of the embouchure hole. This works well with a straight, long and sharp blowing edge to generate maximum volume. A larger embouchure will extend the effect even further.

To some players, a headjoint that is too free-blowing and optimized for volume does not provide enough resistance for tone color changes and lacks core and warmth. They may also find soft passages difficult to control and the tone airy. Too much undercutting can also make the high notes sound thin and metallic. A razor-sharp front edge does not help the matter either. The balance between free-blowing and too free-blowing is delicate and means different things to different people.

The development of the Type 3 style embouchure hole began with undercutting the traditional Type 2 hole. Gradually, the diagonals became longer and morphed into a more rectangular shape with small rounded corners. Albert Cooper was one of the early proponents of this treatment, but he did not considerably change the outer shape. A rounded rectangle could still be recognized, especially when steep overcutting was implemented on both sides. This created an optical illusion that the embouchure was still rounded. When the undercutting extended to the bottom of the front edge, the internal geometry became more rectangular. This shape vastly changed the behavior of the air current as it enters the tube. The science to explore this dynamic phenomenon is complicated and inconclusive. The method for flute making is always trial and error. Empirical knowledge is very useful to headjoint makers, and it is passed down from master to student.

The Type 2 embouchure has been in use the longest. It has been used uninterrupted from Louis Lot’s time until today. Good examples of this style of embouchure are found on vintage Haynes and Powell flutes. The concept of the modern traditional cut is akin to the same design, perhaps with some small modifications, such as undercutting and a tiny amount of overcutting. The shape of a Type 2 embouchure is difficult to describe. I think of each half of the embouchure as the letter “U” lying on its side, the front and back edges slightly curved to form a rounded rectangle. The corner radii are larger than that of the Type 3’s, and the diagonal distances shorter. There is no undercutting on vintage examples, and the wall height tends to be lower. The lipplate is also wider front to back.

Variations of this kind of embouchure design were played by most American flutists up to the mid-1970s. Flutists who have not experienced the traditional embouchure hole may find it stuffy and unresponsive. They may, however, appreciate a different quality of tone–a sweeter, smaller, darker and more focused sound. The lack of undercutting and a wider lipplate create more resistance. The lower wall favors an easier third register in exchange for a less pronounced bottom. The traditional Type 2 embouchure hole demands much of a flutist’s attention and understanding in exchange for beauty and evenness of tone.

The principal acoustic difference between a Type 2 and a Type 3 embouchure is actually at the front edge and not so much the corners. In my experience, the acoustic subtleties rest with the center portion of the front edge. Type 3 approaches a straight line while Type 2 has a slight curve. When comparing the same area between a Type 2 and Type 1, the difference is even more exaggerated. As Boehm has stated, “the long [front] edge allowed more air to be effective.” It seems that a longer length of arc that approaches a straight line is desirable.

The front top edge and the front bottom edge of the embouchure hole form an area that is the front wall. The combined size, shape and angle of this wall is important since it is a bridge the airstream must cross when coming through the lips and into the flute. Modern designs gravitate towards a straight flat wall surface for quick response and volume. The front wall on traditional examples is made of intricate compound curves and has a small target area with the intention of producing a beautiful tone. It is very difficult to duplicate a traditional embouchure because of its unexpected complexity. The sweet spot is not easy to find unless the performer is well accustomed to this sort of headjoint.

Boehm was engrossed with the idea of  producing more power on his flute. After years of experimenting, he concluded that a long front edge was the answer. However, he made his very first cylindrical metal flute (1847) with an oval embouchure hole (Type 1) on a boxwood barrel. The oval design can be found on flutes by early American makers, such as Badger and Berteling. They are also found on most Rudall Carte flutes up to at least the 1950s, and all the wood flutes of Louis Lot and Godfroy. For modern flutists, the oval embouchure hole may be extremely difficult to manage, especially if it is small. A large oval hole, such as on a Rudall Carte wood flute, will produce a very strong sound as demonstrated by many fine British players of earlier generations. There are still a small number of flutists today who play Rudall Carte Boehm system wood flutes with spectacular results.

In my experience, a small oval hole on a boxwood headjoint paired with a metal Boehm flute body is quite suitable for playing Baroque music. It makes the large leaps in the Telemann Fantasias sound easy, secure and light. The tone is intimate and warm, simulating the sensitivities of a Baroque flute. A slower air stream is required. The musical possibilities of this type of embouchure design are not available on the others.

The Type 4 embouchure design has more to do with the outside of the hole than the hole itself. It may have originated in Germany as the Reform Embouchure, where raised areas on the sides of the embouchure channel the air stream into the front of the blowing edge. There are many different configurations based on this concept, sometimes called waved or winged headjoints. Similar devices are often found on large flutes and piccolos. The shapes, sizes, and locations of these implements are quite varied. Depending on the design of the wings, they serve different functions such as increasing the wall height, channeling air to the front at the correct angle, controlling the turbulence at the exit point of the airstream, and supporting the muscles of the lower lip. Sometimes these devices are added on, and other times are a part of the lipplate. Flutists who depend on these unique apparatuses may find switching to headjoints without them challenging.

The evolution of embouchure design from Type 1 to Type 4 is largely a quest for more volume. All the design elements point to that end. After all, Boehm’s invention was much inspired by Charles Nicholson’s powerful tone. (He played on a modified English conical bore wood flute.) The by-product of  the search for power is brightness. Perhaps the insurgence of wood flutes in the United States from around the start of the second millennium was a way to resist this trend. Designing an embouchure hole is a balancing act. In the end, it is a personal choice.


Copyright © 2019 David Chu

This article was first published in Pipeline, summer 2019.

For more information please email Alan Weiss at