In this series addressing the mysteries of the mouthpiece, it has been suggested that the ideal mouthpiece is one which is comfortable and which allows the trombonist to accomplish what he or she is trying to do with a minimum of fuss and muss. The previous installment detailed how variations in the elements of mouthpiece design produce different effects; this one will propose a method to systematically measure those elements.
Although choosing among different mouthpieces is inherently subjective, objective information can aid the process. If you are seeking a particular result from a new mouthpiece, you should know how the elements of that mouthpiece match up with your desires. For example, you might want to ease playing in the lower registers by trying a deeper cup or a larger rim, or you might want to change resistance by trying a different bore size.
Your starting point is the characteristics of the mouthpiece(s) you currently use. Terms like "deeper," "wider," "shallower," etc. are all relative--and in practice what they relate to is what you are accustomed to. The trick is to quantify those characteristics so that you can know exactly how much of a difference there is between one design and another. Although there is much information about mouthpiece dimensions available in resources discussed previously, sorting through them to get answers about specific mouthpieces can be tedious and confusing.
No two manufacturers use the same system of classification for mouthpiece designs and they may use different units of measurement as well. At best, one manufacturer may say model X is equivalent to someone else's model Y. The available information is often scanty. It may be possible to find out rim diameter and bore size for a particular model, but other measurements like rim thickness, mouthpiece weight, throat size, etc. may be unknown or unavailable.
Some of the terms used to describe mouthpieces are inexact. When does a "C" cup begin to shade into a "V"- or is it more of a "U"? How deep is a deep cup, and is it as deep as another brand's deep cup? There are currently no easy answers to such questions.
Adding to the confusion, some manufacturers try to describe the kind of sound a mouthpiece will produce, and the type of music with which it is compatible. This is of limited helpfulness since such descriptions are inherently subjective -- the effect is a bit like reading a wine review!
This series began with an analogy between mouthpieces and shoes. Imagine what buying shoes would be like if shoemakers permitted the same ambiguities we're faced with in choosing mouthpieces! Although shoes come in all kinds of styles, colors, materials, etc. they can be grouped and compared on the basis of a set of standard measurements that everyone uses. I'd like to propose something comparable for mouthpieces. It's a system of measurements that don't require expensive hardware, and it can be applied to any trombone mouthpiece design from any maker.
The system focuses on the following elements: rim inner diameter, rim outer diameter, rim thickness, cup depth, throat depth, and bore diameter. Elements such as rim contour, shank size, weight, plating etc., are not negligible but they are of secondary importance to the elements selected above. The rim dimensions affect how the mouthpiece rests on the lips (the embouchure). The cup, throat, and bore dimensions affect how air moves through the mouthpiece (the airstream).
Measurements I made of 5 different trombone mouthpieces are listed in Table 1 . My personal experience is that they all feel and play quite differently from each other. I expected this given how different they are from each other, but I was surprised to find how small some of the measured differences between them were compared to the differences I perceived. This suggests that differences in mouthpiece dimensions, even a slight one, can be more critical than is generally believed.
The measurements listed in Table 1 can be made with some simple tools: a metric ruler, a U.S. Lincoln penny, and some paper. (For those who do not have access to American coinage, a U.S. penny is a circular coin ~19 mm in diameter.) I've chosen the metric system for these measurements because A) metric units can be more easily manipulated than those of the English system; and B) the tools specified can measure them with sufficient accuracy for this purpose.
Let's start with the rim. Lay the ruler across the rim, and measure the inner and outer diameters. When you have measured the diameters, subtract the inner rim diameter from the outer and divide by two to obtain the thickness of the rim. (It can also be measured directly for a cross-check.)
Cup depth and throat depth are harder to measure as they are determined by the inner curves of the mouthpiece, which can vary greatly between designs. In this system I arbitrarily define cup depth as the distance from an imaginary line drawn across the rim's crown straight down to the bottom surface of the penny lying centered in the bottom of the cup. (Everett, 1968) Throat depth is defined as the distance from the bottom of that same penny down to the narrowest point in the bore. Continuing from that point to the end of the mouthpiece is defined as the length of the back bore.
To obtain cup and bore measurements, start with a piece of paper roughly 30 mm wide and a little longer than the mouthpiece in question. Roll the paper lengthwise way into a cylinder just small enough to fit through the narrowest part of the mouthpiece bore. Slide it up through the back bore until it sticks out into the cup. (You may have to re-roll the paper to get it to fit. The bore of a trombone mouthpiece narrows to roughly the size of a soda straw.) Use the ruler to measure the diameter of the rolled paper cylinder. It should correspond to the diameter of the narrowest part of the bore.
Next put the mouthpiece rim-down on a flat surface with the paper still in the bore. Position the paper so it is against the surface the mouthpiece is sitting on (Position 1). Make a mark on the paper with a pen or pencil right where it sticks out of the shank, and label it "A."
Pick up the mouthpiece and turn it rim-side up. Put the penny on top of the paper cylinder and slowly push down on it until the coin is resting centered in the bottom of the cup with the cylinder flush up against the underside of the coin (Position 2). Make a new mark on the cylinder where it sticks out of the shank, and label it "B."
Remove the penny for the next step. Carefully pull the cylinder farther through the shank until the end that was against the penny is just even with the narrowest part of the bore (Position 3). You'll have to do this by eye. Make a new mark on the cylinder, and label it "C."
Take the paper cylinder out of the mouthpiece. Use the ruler to measure the distance from A to B: this should be the depth of the cup. The distance from B to C is the depth of the throat. Measuring from C to the end of the cylinder gives the length of the back bore.
You can obtain additional information if you have access to an accurate scale. All of the mouthpieces listed in Table 1 (and two Giardinelli Tone Intensifier rings) were weighed on a Mettler PN1210 balance which was also used to measure their internal volume, from the crown to the end of the shank. The results are listed in Table 2.
Measuring volume was done by wrapping wax parafilm tightly across the rim of each mouthpiece to seal it. One at a time, each mouthpiece was placed rim down on the balance which was then adjusted to read zero. The mouthpiece was filled all the way to the end of the shank with water, and the weight of the water was measured directly. The weight of the water corresponds to the internal volume of the mouthpiece, since one gram of water has a volume of one milliliter (1 cubic centimeter), by definition.
Obtaining measurements of the cup, throat and bore is somewhat troublesome because of the difficulty in determining exactly where they begin and end. Fink cites research by the Conn Corporation which denotes the curvature of the transition from the cup to the throat as the "shoulder" and the narrowest part of the throat bore as the "orifice." (Fink, 1977) In the absence of a way of distinguishing the curvature change of the shoulder with precision, the coin/paper method has the advantages of simplicity and consistency.
It may also provide a more defined way to describe cup shape, "C" vs. "V." Cup depth and throat depth could be combined with the measurement of the inner rim diameter to produce a ratio or ratios. Mouthpieces with ratios within a certain range of width to depth up to some point of demarcation could be considered to be "C" cups; ratios on the other side would be considered "V." Setting the point of demarcation would require both an extensive survey of the ratios of different mouthpiece designs to discover what their range is, and a general consensus among mouthpiece makers and users on where to 'draw the line.'
An inexpensive tool which could measure both the diameter of the orifice and its location directly would be useful. Lacking that, making a series of measurements using the technique described above should yield an average which approaches accuracy.
This system of measurements was developed as a response to the incomplete and ambiguous information commonly used to describe trombone mouthpieces today. As such, there is no reason it or a comparable system could not be adopted as a universal standard, though it will take some additional work to extend it to cover the whole range of mouthpiece types, from trumpets to tubas. Something that might be almost as useful either by itself or as a supplement would be for each manufacturer to make available accurate scale cross-section drawings of their mouthpieces.
Finally, although this system can make it easier to compare mouthpiece designs, it still does not do away with the need to actually try them, no more than it would be a good idea to buy shoes by size alone, without trying them on. Measurements do make the process easier though, in both cases. You don't have to try on every black Oxford in the store if you know you take a size 11-D.
If you have several trombone mouthpieces lying around, make your own set of measurements. You can take the information in last month's installment and see how it compares with the results you get; you may be surprised. You may find for example that different throat depths have more of an effect on your playing than different cup depths. You might find that two mouthpieces with identical rim diameters play very differently for you simply because of different amounts of rim bite or a different contour. If or when you are in the market for a new mouthpiece, you'll have a better idea of what to look for.
Those of you with trombone students might want to demonstrate these measurements for them and let them try making their own set as an exercise. It will give them a better appreciation of their equipment and will enable them to make informed choices when they go shopping for something new.
If you have all of your students do this and if you keep track of the results, over time you may begin to get a measure of which particular mouthpieces seem to work best for certain players, based on their physical parameters, skill levels, and other factors. Conversely, you may find it doesn't seem to make that much difference compared to other factors, like practice time, model of trombone, etc.. In either case, you'll be able to have more confidence in the answers you give your students when they ask about mouthpieces.
You can also use different mouthpieces as an exercise from time to time to make them think about what they're doing with their embouchures and breathing. Letting a student try otherwise identical mouthpieces with different bore sizes, for example, may give them a much better appreciation of resistance. Trying a different rim thickness may make them more aware of how they place their usual mouthpiece on their lips. Combined with quantitative data on just how a mouthpiece differs from what they are used to, this kind of experience can give them (and you) a better handle on how much difference the mouthpiece makes compared to their own efforts.
About the Author...
Larry Roth began playing the trombone in the fifth grade, and has yet to succeeded in getting away from it. A technician for a State Health Department, Roth is a 'Weekend Warrior" with the Delmar Community Orchestra, the H-M-S Marching Band, the Starliters Big Band, and the Greg Nazarian Big Band. Contact: email@example.com.