Vocal Resonation - Factors Affecting Resonators

Factors Affecting Resonators

There are a number of factors which determine the resonance characteristics of a resonator. Included among them are the following: size, shape, type of opening, composition and thickness of the walls, surface, and combined resonators. The quality of a sound can be appreciably changed by rather small variations in these conditioning factors.

In general, the larger a resonator is, the lower the frequency it will respond to; the greater the volume of air, the lower its pitch. But the pitch also will be affected by the shape of resonator and by the size of opening and amount of lip or neck the resonator has.

A conical shaped resonator, such as a megaphone, tends to amplify all pitches indiscriminately. A cylindrical shaped resonator is affected primarily by the length of the tube through which the sound wave travels. A spherical resonator will be affected by the amount of opening it has and by whether or not that opening has a lip.

Three factors relating to the walls of a resonator will affect how it functions: the material it is made of, the thickness of its walls, and the type of surface it has. The resonance characteristics of a musical instrument obviously will vary with different materials and the amount of material used will have some effect.

Of special importance to singing is the relationship of the surface of a resonator to its tonal characteristics. Resonators can be highly selective-meaning that they will respond to only one frequency (or multiples of it)-or they can be universal-meaning that they can respond to a broad range of frequencies. In general, the harder the surface of the resonator, the more selective it will be, and the softer the surface, the more universal it will become. " hard resonator will respond only when the vibrator contains an overtone that is exactly in tune with the resonator, while a soft resonator permits a wide range of fundamentals to pass through un-dampened but adds its own frequency as on overtone, harmonic or inharmonic as the case may be."

Hardness carried to the extreme will result in a penetrating tone with a few very strong high partials. Softness carried to the extreme will result in a mushy, non-directional tone of little character. Between these two extremes lies a whole gamut of tonal possibilities.

The final factor to be mentioned is the effect of joining two or more resonators together. In general the effect of joining two or more resonators is that the resonant frequency of each is lowered in different proportions according to their capacities, their orifices, and so forth. The rules governing combined resonators apply to the human voice, for the throat and mouth and sometimes the nose function in this manner.