It’s not only the throat’s diameter which is of importance, however, as the radius at the point where the cup meets the backbore is also critical. This is because the air at this point is about to be constrained by the smaller throat diameter and the radius at this point determines how the air’s path is to be controlled by the contours of the mouthpiece.

Undoubtedly, wider-bored throats reduce the back pressure felt by the player and allows more air to be pushed into the instrument, thus enabling louder playing. However, using more air calls for greater exertion and is more tiring. The freedom of blowing has a drawback in that mouthpieces with wide throats tend to be more difficult to control.

Mouthpieces with a semi-spherical cup, such as the trumpet can have a wide range of different radii at the point where the cup and backbore meet and in the PeakTone model, this feature is referred to the Throat Entry Diameter. The diagram below illustrates the feature on several tenor instruments.

The Cups and Throats of Several Mouthpiece Types

In the illustration above, the Baroque trumpet can be seen to have a tight Throat Entry Radius while the French horn has such a large radius at this point that the cup passes almost imperceptibly into the backbore. The trumpet and cornet sit between these with the trumpet mouthpiece having the tighter radius of the two. This radius is also partially responsible for the quality of the tone produced with a tight radius allowing for a brighter, more piercing sound output and the less-prominent radii, such as are seen on the French horns, leading to more mellow tone richer in lower partials. Tubas also generally have very smooth transitions from the cup into the backbore, somewhat like that of the cornet shown above.

The very tight radius at the throat of the Baroque trumpet provides a level of definition which enables the player to pick out individual notes in the range where it is utilised as the harmonic series in this range has individual partials placed much more-closely spaced.

A mouthpiece’s throat diameter also has some impact on the performance of the mouthpiece-trumpet combination, large throats said to sharpen the notes in the high register while very-large throats may also sharpen the lower register. A large throat will allow the player to push more air through the mouthpiece but will result in greater difficulty in execising control during quiet passages.

A smaller throat does restrict the air flow and can have the effect of flattening the higher register and sharpening the lower. It will also have an effect on tone, resulting in a thinner-sounding output.

Typical throat diameters for trumpet mouthpieces are around 5.6 mm (0.14 in) while those for the tuba are around 7.6 mm (0.30 in). There is no doubt that slight changes in throat diameter will have considerable effects on the overall feel of a mouthpiece.

As with all features discussed in these pages, throat characteristics must be considered alongside all the other elements of a mouthpiece  as each has an impact on all the others.

When the throat setting is selected, the selection box shown below is displayed. The three sliders provided allow you to modify the throat diameter, the throat radius, which is the radius between the cup’s shoulder and the backbore and the depth of the throat. Larger throat diameters reduce the back pressure from the mouthpiece which allow air to be blown through the mouthpiece with less pressure. This will have the effect of making it easier to play louder but more difficult to play in the upper register, as well as for long periods. The throat radius affects the ease with which one might slide seamlessly from one note to another , making the demarkation between notes less marked. The cup depth is a feature which affects the resistance to airflow through the mouthpiece, increasing the backpressure.

The active diagram below provides access to the three settings so that you may investigate these interactively. The effect of moving the throat depth slider is best seen on the lower of the two images, the one showing the full mouthpiece.

<div class="odoko-diagram-sliders">
  <div id="sliders-simple-throat_diameter-throat_radius-throat_depth-cup" data-params="throat_diameter,throat_radius,throat_depth">
  </div>
</div>

<div class="odoko-diagram-sliders">
  <div id="sliders-simple-throat_diameter-throat_radius-throat_depth-horiz" data-params="throat_diameter,throat_radius,throat_depth">
  </div>
</div>