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Mouthpiece Nomenclature Guide

Behn Clarinet Mouthpiece Design
mouth-piece [mouth-pees]


  1. the top piece of a musical wind instrument. 

  2. A piece or part to which a "reed" is attached, and blown into, to become the source of vibration and sound.

  3. The top part of single reed instrument, made from a variety of materials such as hard rubber, wood, metal, glass, and plastic. Hard rubber is considered to have the finest resonance characteristics. 

Below we will discuss the many components of mouthpiece technology and how they relate to one another.

Mouthpiece Design

A mouthpiece design consists of many elements and it is important to note that everything influences the playing experience. The bore size, length, the chamber volume, the baffle depth, and facing all interact and influence each other. 

Behn Mouthpieces:  Cross-section of a Clarinet Mouthpiece.  Learn the various parts of the mouthpiece, including—tip, baffle, side rail, side wall, throat, bore, exit bore, facing, table, window, beak, tenon

The design of a mouthpiece consists of the chamberbore, and facing.

Please note: Facings are not designs. A facing is part of a mouthpiece's design. A good facing, however, allows the player to realize the full scope of the mouthpiece design. So even though it is a small part, it is important nonetheless.

A mouthpiece's design is the sum of all internal and external shapes. The material in conjunction with the bore's length, taper, radius, and the chamber's volume, sidewall construction, baffle depth, and throat shape, all come together to create a mouthpiece's unique design. The facing on the other hand, in conjunction with side rail thickness and tip rail thickness, enables the player's reed to interface with his/her artistry.

Chamber consists of the bafflesidewalls, and throat. The chamber must work in harmony with both the facing and the natural resonance characteristics of the hard rubber, and it should be constructed in a manner to best suit the tonal concepts of the player. The chamber can be made with a variety of shapes, depths, and lengths, as long as the total volume of the mouthpiece is correct. If the chamber's volume is too large, the bore needs to be smaller to allow for proper tuning characteristics. Larger chambers tend to create a broader and freer tone with lower tuning tendencies, while smaller chambers add some resistance, increase tonal concentration, and raise pitch.

Baffle is one of the most important parts of a mouthpiece’s design. It is the ramp that slopes down into the bore. A baffle’s depth and shape are crucial and affect pitch, sound and response. Baffles usually have concavities on two axes, and their radii are very important. A baffle with less depth, or a smaller radius down into the bore will create a more resonant, focused sound, and quicker response. A baffle with a deeper, more scooped shape will create a more mellow sound, with a slower initial tone response. The concavity that runs across the baffle from either sidewall is important in creating a multi-dimensional sound. Baffles that are flat tend to create sounds with limited scope.

Working-resistance isn't a physical design element, but it is an important part of mouthpiece design. Essentially, working-resistance comes as a result of how facing length and curvature, window width, rail thickness, baffle depth, bore volume and chamber volume interact with one another. If a mouthpiece is too free, it is difficult to control, therefore, response and reliability suffer. If a mouthpiece is too resistant, it becomes restrictive to the player's musical input, response becomes difficult, and biting may ensue. So, a properly balanced working-resistance is extremely important in order to produce the ideal playing experience.  

It is important, now, to recognize how baffle depth influences resistance. First, please understand that as air travels into the mouthpiece, forward and back pressure waves react against the baffle. These combined waves are reflected off of the baffle and push the reed away from the facing. If the baffle is very deep, the forward and back pressure waves aren't as strong because they have a further distance to travel. So, deeper baffles cause less "bounce" or "pushback" against the reed. This is what is responsible for the added feeling of resistance. However, if a baffle is "high", meaning closer to the reed, then these combined reflected waves influence the reed with a stronger "pushback" because of the shorter distance to the reed. So in general terms, higher baffles are faster responding, add resonance, and reduce resistance.  

However, this can lead up to a very interesting phenomenon. If a baffle's contour near the tip is very high, as seen in mouthpieces with large tip-rollovers, this can create a very small "flight envelope".  In other words, the sound is either on or off. This means that there is little space for nuance or variation. This can be a liability because it limits a player's ability to add breadth and scope to his or her artistry.  

But upper baffle height adds point, sparkle, focus, and bite-free freedom, which are all good things. So to access these highly sought after elements of baffle height and avoid the bad, we must balance upper baffle height with lower baffle depth. This is done by making a complex surface contour, an "S-curve" baffle shape which consists of an upper baffle height that rolls down into a deeper hollow in the lower baffle. This novel baffle design provides a "cushion" effect in the playing experience. It "softens" the pressure waves thereby giving the player access to a wider variety of sounds and a larger range of expression.

Baffles, pressure waves, resistance, and surface contours can be tricky!

Sidewalls greatly affect a mouthpiece's playability. The distance between sidewalls influences a mouthpiece's tonal character and resistance level. Sidewalls that are closer together can create a more stable playing platform, but the danger is that if the sidewalls are too close together, the sound becomes tight and inflexible. If the sidewalls are too far apart, the important working-resistance is reduced and the sound becomes washed out. Generally, sidewalls that are closer together require softer reeds, and sidewalls that are farther apart require firmer reeds.

Throat is in part responsible for the sound’s concentration. The sidewalls run down the chamber to the narrowest point at the throat. This is at the juncture between the chamber and the bore. A narrow throat creates a more concentrated sound and a wide throat creates a broader sound. Throats can be configured in any way—round, square, parallel (H-frame), or wider at the bottom and narrower at the top (A-frame). Clarinet mouthpieces are typically made with throats that are either H-frame or A-frame in construct.  The concept of A-framing a throat is to combine tonal concentration with freedom and flexibility. H-frame throats, depending on width, allow one to concentrate on a specific playing attribute. For example, wider throats will predominantly make for a free, flexible, and broadened tone ("Ahh" vowel sound), whereas narrower throats will add working resistance, require softer reeds, add stability, and produce a narrower tone ("Eee" vowel sound).

Bore serves the chamber. Indeed the bore influences the sound, but its primary role is to balance the chamber to create the perfect total volume. Volume size affects pitch and this is the bore's greatest role. If a bore is too big, the pitch can go flat and the sound can become diffused. If the bore is smaller, pitch will rise and the sound can become more resonant. If the bore is too small, the mouthpiece may lack depth and size of sound and the pitch will most likely be very sharp.

Facing has influence over everything. The facing is the curve that the reed vibrates against.  It runs the entire length from where it leaves the flat surface of the table all the way up to the tip of the mouthpiece. A facing's length, opening, nature, efficiency, and symmetry will affect the playability of the mouthpiece. If the facing length is short, then the resistance will be high. With shorter facing lengths, softer reeds are required. Smaller curvatures can also give the player a sense that the tip is more open in feel. However, with a longer facing length, the resistance decreases. Longer facings with flatter curvatures require harder reeds and can give the player a sense that the tip is more closed in feel.

Rails that are wider create a larger platform for the reed to vibrate against. This larger surface area creates an easier platform for clarinetists to align the reed to the mouthpiece with positive results. Due to its nature of being more forgiving, they can be helpful for clarinetist's who's ability to see up close, or in less then perfect light conditions isn't what it once was. Rails that are narrower do require extra care when aligning the reed on the mouthpiece, but allow for faster response. 

Imagine riding a bicycle designed for road racing. It has very high pressure, very narrow tires. It has very low rolling resistance, highly efficient pedaling-power, high speed, quick response, and one feels the road more acutely. Whereas when one rides a bicycle meant for casual recreation or trail use, the tires are much wider, and the air pressure is lower as well. The result is that due to decreased efficiency, it takes more effort to pedal up to speed, and the bicycle responds slower and sluggishly. However, the riding experience is smooth, comfortable and gently rolls over the bumps on the road with little feeling on the bottom.

And so mouthpiece rail thickness influences response, efficiency and the overall experience of playing the clarinet. Essentially (all other things being equal) thinner rails create a fast experience; response is quicker, sound is highly resonant and clear, freedom is enhanced, and care is needed to align the reed to the mouthpiece. With wide rails, response slows down, air resistance increases, resonance is muted, sound becomes covered, and less care is needed to align the reed to the mouthpiece. Very narrow to very wide rails can all work well, but the key is to balance the facing and chamber dimensions so that they are all working sympathetically with one another. Therefore, as rail width increases, resistance must be reduced either from the facing curvature, or the internal details in the chamber or bore.

Window shape influences resistance and blow through. Wider windows have less resistance, they blow through easier, yet they can cause the sound to be less focused and compact. Narrower windows help concentrate the sound, but they add resistance and reduce blow through. Ideally, to keep the center of the sound beautifully defined, a narrower window coupled with a, resistance reducing, longer facing will allow for a nice balance of freedom, blow through, and quality of sound.  

Length refers to the point where the curve departs from the table. It is the part of the curve that is farthest from the tip. Generally, a facing with a long length feels closer and free whereas a facing with a short curve will feel more open and resistant.

Opening is the gap between the tip of the reed and the tip of the mouthpiece. An open mouthpiece is usually fitted with a longer, flatter curve to reduce resistance. A close mouthpiece is usually fitted with a slightly more extreme nature to the curve to create the correct amount of working resistance. Generally, more open mouthpieces require greater embouchure pressure to properly focus the sound, and they require more embouchure "maintenance" keep the sound under control. More close mouthpieces require less embouchure pressure and tend to have more hold. Generally, people seeking a dark and covered tone, or a wider range of flexibility prefer more open facings.  

Nature refers to the type of curve. Curves can vary substantially, as some are nearly flat and others have a more extreme curvature. Curves that are flatter tend to be free blowing and curves that are more extreme tend to have more resistance. The key is to match the nature of the curve to the tip opening and length.


Efficiency occurs when the mouthpiece holds the sound with the least amount of embouchure pressure. When the length, nature of curve and tip opening are all working together, the facing becomes efficient. An efficient curve creates a fluid and resonant playing experience.

Symmetry refers to the balanced relationship between side rails. If a facing's left rail has a different curvature than the right rail, the mouthpiece is effectively detuned and loses resonance. A facing that has symmetrical rails is more likely to respond reliably, sound clear and project easily.

What about the Material?

The material is the foundation of a mouthpiece and has important influence over all playing characteristics. Material affects everything from tone to response and has a large influence over the playing experience. Over the years, makers have experimented with a variety of materials to find the perfect mouthpiece.

Wood was used before the advent of hard rubber and was plagued with problems. As a wood mouthpiece warms up, its dimensions change due to uneven expansion tendencies and this causes response and intonation problems. The mouthpiece can easily “warp” and this can cause a disastrous relationship between the reed and facing. Wood can create a variety of tone shapes and colors, but it is usually responsible for a colorful warm sound, easy response and good blow-through. A good wood mouthpiece can sound very pleasing…when it works properly.

Ivory was used in the old days in an attempt to find a material that sounded good but was more stable than wood. Ivory is more dense than wood and has a more resistant feel. The sound has depth and point, but the response is not as quick.

Hard Rubber, also known as Ebonite, Vulcanite, and sometimes as India rubber, Steel Ebonite, and Caoutchouc, replaced wood and ivory as the new wonder material. Hard rubber is stable and has a wonderful acoustic range. Depending on its density, a mouthpiece's sound, response, and resistance can be modified to suit most tonal concepts. Since its inception, hard rubber has remained the chosen material for clarinet mouthpieces.

Glass provides a very different playing experience. It is more resistant to the blow-through and it can produce a dark and colorful flute like sound. Usually, when playing on glass mouthpieces, it is necessary to play on softer and very vibrant reeds.

Metal in the form of brass, bronze, stainless steel or aluminum is often plated gold or silver and is used much more in saxophone mouthpieces for its quick to resonate sound. It is typically paired with a higher baffle for added brightness and volume.

Plastic is commonly used in student mouthpieces for its ease of manufacturing and therefore low cost.  As there are many types of plastics, there are many ranges of sounds. However, "conventional wisdom" asserts that plastic is not capable of producing the depth and range of sounds that rubber can produce.  This is in fact not the case.  Some plastics sound quite good, and when properly matched to the right design which augments the plastic's resonance characteristics, a good playing experience can be obtained. The key is that plastic must be enhanced by its design specifications in order to have professional playing attributes.   

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