Impedance

Impedance is the amount of resistance an object has to alternating current. In the case of musical performance, the alternating current(s) are sound waves of a frequency and amplitude that combine to produce music.

It is fundamental to our work that every element in the system of performance not only has a pitch center, but also exhibits an impedance which is affected by but not solely dependent on its pitch center. The impedance can be adjusted in each element to help the overall balance and efficiency in the system and enhance performance.

The most efficient and pleasing musical experience for both the player and the audience is possible when the pitch center of all the elements in performance is optimum, and the impedance of these elements matches or balances. This is something that may be difficult or impossible to measure, but again, it can usually be felt and heard immediately by both the player and the audience.

Impedance of the Player

The impedance (and also the pitch center) of a player is determined by many factors: physical, emotional, environmental, etc.

Most players who have played for any length of time have experienced that a given mouthpiece or instrument will seldom feel or sound exactly the same from one day to the next. But what has changed? It is obviously not the equipment (which is made out of metal), but rather something in the player. Obvious examples would include one’s physical condition, stress level, emotional state, or any one of many possible factors both tangible and intangible. When a player is having a “bad day,” even if the initial cause is not physical, there are physical symptoms that will manifest in the player. These symptoms often include excessive tension and/or misalignment in the body.

The number of ways players may experience changes in impedance (resistance) in themselves through changes in thier body use during performance far outnumber possible changes in the equipment. Please refer to the section Pitch Center, Body Use, and Resonance for more specifics on identifying the physical symptoms of stress relative to alignment and body-use during performance.

Impedance of Equipment

The impedance of a mouthpiece or instrument is determined by its physical characteristics. The more obvious ways to alter the impedance of an instrument (or a part of an instrument) include changes in wall thickness, brace placement, material used, rates of taper, radius of bends, etc.

Bore Size

Because we receive so many questions about this topic, it is worth noting that when considering all the design details that help determine the impedance (resistance) of an instrument, the bore size of an instrument, if it is within a reasonable range, is fairly inconsequential.

Most companies that mass produce instruments offer instruments with a few bore sizes, with one size usually being the most popular. This option exists because changing bore size is an inexpensive way to change the playing characteristics of an instrument without changing any tooling in the manufacturing process. In our experience, the flaw in this reasoning is that changing bore size alone, without addressing a corresponding change in many other design elements, can adversely change the conceptual relationship between the various parts of the instrument, and therefore adversely affect its overall resonance.

In the case of Monette instruments, the different models of custom instruments we produce not only have different bore sizes, but also have correspondingly different slide tubing, top and bottom valve caps, finger buttons, leadpipes, ballisters, bells, tuning slides, bell wires, and so on. There are also corresponding changes in shapes of bell and tuning slide bends, weights and positions of braces, tapers and thickness of leadpipes and bells, etc. that must be considered in order to keep the impedance, pitch center, and musical concept of each part of the instrument in line with its overall design. For more information, please refer to the Monette instrument section.

The Impedance of the Room

The impedance of the room is determined by various factors, including the shape, size, temperature, humidity, altitude, and reflectivity of the material in the room.

We often meet trumpet teachers who practice and teach in small studios that are carpeted, have low, “acoustic” tile ceilings, and sometimes even have cloth curtains over the windows. When playing in rooms such as this, it is virtually impossible to re-create the same sound, feeling of resistance, and type of response one would experience in a real auditorium or concert hall.

When playing in a room that is full of sound-absorbing material, instruments that might otherwise feel comfortable to the player can feel “stuffy” and sound “dead.” Even just talking with someone across a room like this can be more work than desirable. We suggest adding to the reflectivity of the room, by exposing glass windows, rolling up rugs, and replacing the absorbent “acoustic” ceiling tiles with reflective plastic-coated ceiling tiles, available at most home stores. The more open and resonant the room, the more open and resonant one experiences the equipment and the performance. The “deader” the room, the more resistance one will experience when using equipment that is designed for use in a quality acoustic situation.

We strongly suggest playing in rooms made for musical communication as often as possible, and we also suggest trying to recreate the sound and resistance one experiences in these settings in whatever rooms you regularly play or practice.

Other environmental factors that dramatically affect the impedance of the room are temperature, altitude, and humidity. Most players find a humidity between 50% and 70% to be optimum.* A change in air pressure and density can be quite disorienting when playing as well. Anyone who has performed at sea level and also at high elevations is familiar with the changes in resistance (and capacity) when changing altitudes.

The Impedance of the Audience

When a performance is inspired, the excitement and energy of the performer(s) is transmitted to the audience in a way that “completes the circuit.” This connection and “impedance match” between the performer and the audience can totally overcome other obstacles that may exist in the performance system. This is also true even if the audience is oneself. Some performers transcend financial hardship, poor equipment, or other obstacles and give the performance of a lifetime simply by virtue of the fact that their musical message and ability to communicate is so strong.

Most of us at one time or another have experienced performances that were less than ideal. A performer may play note perfect for example, but at the same time be so uninspired that there is no meaningful communication between those on stage and those in the audience. Other performances may be less “perfect,” but a spontaneity and excitement can still carry both the audience and the performer to a heightened awareness and appreciation for the music.

One of the things that makes musical performance such a potentially magical experience is that the performer has the opportunity at any given moment to communicate something of value to the audience that makes them immediately more receptive to the experience. Unlike the visual arts, music is “in the moment,” which may increase the potential for either the performers or the audience to transcend their normal awareness and grow from the experience. While an impedance mismatch may be felt in the pit of the performer’s stomach, an impedance match can usually be seen and felt in the eyes and smiles of everyone involved in the performance.

*For a more in-depth discussion of the effects of humidity and temperature on projection of sound, please refer to Cyril M. Harris’ excellent paper “Absorption of Sound in Air versus Humidity and Temperature” from The Journal of the Acoustical Society of America, Vol. 40, No. 1, 1480159, July 1966.