5. The Mouthpiece's Construction

One thing that makes it easy to describe a mouthiece is the fact that it is identical from all sides. So we can just cut through it anywhere to show you a top-to-bottom section.

Section of a Moutpiece

Rim diameter:

The rim diameter indicates the width of the mouthpiece at the uppermost part, from left to right. The interior rim diameter is one of the factors determining how much of your lips will vibrate. The diameter is chosen according to, and this may sound strange, the frequency range you intend to play in the main. Conversely, this means that the mouthpieces of instruments which cover the same franquency range also have mouthpieces of identical width. To clarify: the frequency ranges of trumpet and tuba overlap only minimally, and you can see this just by looking at their mouthpieces with interior rim diameters of 16mm and 31mm, respectively.

Rim width:

This number indicates the width of the moutpiece's upper rim itself. Regarding the width, players' preferences range from narrow to wide. Apart from width, rim contour also plays an important part. Some mouthpieces have a rounded rim, others are shaped to be much flatter. Depending on the shape of your lips, you will have to try a variety of differently contoured rims when you embark on your search for the right one. Only then can you tell which mouthpiece is suitable for the many hours you will spend with it.

If you want to draw up some basic rules, this is how they could read:

The rim contour is also influenced by the rim's interior egde. These rage from acute to rounded edges.

So what does this edge do?
An acute interior egde allows clean and clear entries, but they make smoothly linking notes more difficult. With round edges, it's the other way around. But of course every gradation has different effects, and anyway, the contour is not everything.

There are also:

There seems to be a connection between rims and edges – the rounder the rim, the rounder the edge. The question which rim-edge combination is best for you is one you have to find the answer to yourself.

Now, although all these aspects deserve attention, the main focus when you buy a mouthpiece is the cup

What matters most here are the width, depth and contour of the cup.

Back bore:

As if all this wasn't complicated enough, after having had a look at the section we will now move further down the mouthpiece into the part known as the throat. The throat is the connection between the cup and the back bore. The combined shapes of the throat and the back bore are crucial to the sound of the instrument. The terms narrow, medium narrow, medium, and wide refer to the diameter of the back bore. A standard mouthpiece for beginners will usually have a semi-narrow bore. But it is impossible in this case, too, to tell you what the “perfect“ size is for you. Trying some out is the key. The back bore, which may also be regarded as the beginning of the instrument's conical tube, transitions into the shank.

The shank is the connection between the mouthpiece and the lead pipe. It is important to make sure that the entire apparatus is neither too long nor too short; otherwise playing at perfect pitch is impossible. It is also important that the connection between shank and lead pipe be tight.

Attention!

You can still err in the choice of a shank. If you play the trumpet, the shank won't present you with any problems. If you play the flügelhorn, the trombone, or the euphonium, however, you will have the choice of different types of shank. The types on offer are usually German, American and Yamaha shanks. If you don't know which one is appropriate for you, ask your trusted MI dealer :-).
This list of the different elements alone is probably enough for anyone to realize that choosing a mouthpiece is not a matter of minutes; rather, take some time and try out good number of them. And remember that a mouthpiece in which every element is perfect in itself, but in which the elements are badly proportioned, is useless, too.