Resonator

“ The motion of one has, therefore, an analogy in the motion of the other. In an electrical circuit having a coil and a condenser the moving electricity has a definite inertia and a definite electrical stiffness; hence it will have a definite pitch or frequency for its vibratory motion, just like a tuning-fork; it will act as a resonator. It is obvious, therefore, that an electrical resonator, the pitch of which can be adjusted by adjusting its coil or its condenser or both, is a perfect parallel to the acoustical resonator. ”

“ The stem of the tuning-fork is inserted in the socket F of the sounding-box. The internal increase of pressure induced by the vibrations of the tuning-fork through the sounding-box in the resonator at a has the effect of driving a jet of air gently against the sails of the mill, which consequently rotates. The two-aperture resonator of this apparatus may be replaced by a resonator having but one aperture, which may be formed of a glass ball cut away at one side and cemented to a glass plate having a small hole in the center. ”

“ We will now introduce the temperature of the resonator, and will express through the energy of the resonator and also the intensity of the heat radiation related to it through a stationary state of energy exchange. For this purpose we utilize equation and obtain then for the energy of the resonator:
It is to be observed that we have not here to do with a uniform distribution of energy (cf. fourth lecture) among the various resonators. ”

“ There is not much difficulty in detecting the difference tone by a resonator if it is held, say, close to the reeds of a harmonium, and Helmholtz succeeded in detecting the summation tone by the aid of a resonator. ”

“ In this form the arrangement is called a resonator or auto transformer, and is much used for producing high frequency discharges for medical purposes. The construction of a resonator is as follows: A bare copper wire is wound upon an ebonite or wooden cylinder or frame, and one end of it is connected to the outside of a Leyden jar or battery of Leyden jars, the inner coating of which is connected to one spark ball of the ordinary induction coil. The other spark ball is connected to a point on the above-named copper wire not very far from the lower end. ”

“ The fundamental note C is sung on a vowel sound in front of the instrument; the lowest resonator is proper to that note and the air in it is thrown into corresponding periodic rhythmical vibrations, which are communicated through an intervening membrane to the gas in the capsule at the back of the resonator; but the gas is connected with the lighted jet, the flame of which is reflected in the mirror, the result being that the flame vibrates. ”

“ The dissipation of energy is more rapid when the resonator is immersed in air than it would be in a practically continuous medium, for instance, oil. 2. The dissipation owing to the presence of air renders the difference between magnetic and non-magnetic metals more striking. The first conclusion follows directly from the preceding remarks; the second follows front the two facts that the resonator receives always the same amount of energy, independent of the nature of the metal, and that the magnetism of the metal increases the impedance of the circuit. ”

“ Increased loudness of the voice will not improve its carrying power if the resonator is improperly used; it will often lead to a rise of pitch and the production of a harsh, shrill tone associated with a sense of strain and effort. Aikin claims that by studying the whispering voice we can find for every vowel sound that position of the resonator which gives us the maximum of resonance. By percussing2 the resonator in the position for the production of the various vowel sounds you will observe a distinct difference in the pitch of the note produced. ”

“ Let R and R' be two resonators accurately tuned to the note given by the vibratory body at S. Suppose both resonators at the same instant on the wave-surface, then they both receive, at the same instant, the same phase of vibration, on the planes of their mouths. If two tubes of equal length lead from the resonators and join into one tube just before they reach the ear, E, then the sound-pulses will act together, being of the same phase, and the ear will receive double the action which it would if only one resonator were connected with the ear. ”

“ By examining the results with other positions of his resonator and by other and varied experiments, Hertz was able to prove the existence of definite waves of electro-magnetic and electro-motive forces, to measure their lengths, and to show that they are capable of reflection, refraction, and even polarization by the same laws that hold with the extremely short but enormously rapid vibrations constituting light. ”

“ The apparatus, oscillator and resonator, being immersed in air, or other discontinuous medium, there occurs—as I have pointed out in the description of my recent experiments before the English and French scientific societies—dissipation of energy by what I think might be appropriately called electric sound waves or sound-waves of electrified air. ”

“ Placing or "focusing the voice" I have found to be chiefly [Pg 52] a matter of control and use of the resonator, consisting of chest, pharynx, mouth, and the nasal and head cavities.
A tone lacking in resonance is ineffective,—devoid of carrying power,—is diffuse and unfocused; while a resonant tone, no matter how soft dynamically, has carrying power and is focused in its vibration.
Now "voice placing" depends primarily on correct vowel placing, which in turn depends on proper adjustment of the resonators, which again depends chiefly on the positions and motions of the organs of articulation. ”

“ In respect to resonance, as in other respects, the human voice is far superior to all other instruments, for their resonators are fixed and unchanging, while the human resonator is flexible,—in Helmholtz's words "admits of much variety of form, so that many more qualities of tone can be thus produced than on any instrument of artificial construction." ”

“ A radiator with several swings is less violent at its first impulse than is a momentary emitter; but then the lessened emitting power of a radiator is to be compensated by a correspondingly prolonged duration of vibration on the part of the receiver or absorber, thus rendering the radiator susceptible of tuning to a special similarly-tuned receiver or resonator. ”

“ Initially, let us neglect the radiation absorbed and emitted by the resonators and focus instead on the requirement of thermal equilibrium and its implications for the interaction (collisions) between molecules and electrons. According to the kinetic theory of gases, dynamic equilibrium requires that the average kinetic energy of a resonator equal the average kinetic energy of a freely moving gas molecule. ”

“ No question the micro-resonator is the neatest sweetest wrecking device going. You can expect a lot more of this sort of efficiency now that mankind has the tickler to enable him to use his full potential. ”

“ It depends on the fact that many waves of sound that reach the ear are compound wave systems, built up of constituent waves, each of which is capable of exciting a sensation of a simple tone if it be singled out and reinforced by a resonator (see Sound) , and which may sometimes be heard without a resonator, after special practice and tuition. Thus it appears that the ear must have some arrangement by which it resolves every wave system, however complex, into simple pendular vibrations. When we listen to a sound of any quality we recognize that it is of a certain pitch. ”

“ This task having been disposed of, the solution of the problem was before me.
A physicist, given a number of diapasons and resonators, will find no difficulty in demonstrating that sound is not propagated instantaneously, even in the restricted space of a room. Having set the diapason in vibration, he goes with his resonator to different parts of the room and observes the intensity of the sound. He perceives that it becomes weak in some places, and infers from this that each vibration is annulled by another of later origin, which has reached the spot by a shorter route. ”

“ About 25 per cent. of the diameter of the tube must be added to the length of the air column to make it just one-fourth the wave length. The sound heard in seashells and in other hollow bodies is due to resonance. Vibrations in the air too feeble to affect the ear are intensified by sympathetic vibration until they can be heard. A tuning fork is often mounted upon a box called a resonator, which contains an air column of such dimensions that it reinforces the sound of the fork's sympathetic vibration. ”

“ Those who experience difficulty in perceiving the overtones as separate pitches may use at first special instruments, resonators, which are held against the ear and greatly increase each the intensity of a special overtone. After some practice one becomes aware of the pitch of an overtone without the aid of a resonator. ”

“ Among the many possible resonators are Helmholtz resonators, half-wave or quarter-wave resonators, and solid structures such as tubes, plates, or cavities within the chimneys [24] – [25] . Considering the typical acoustic properties of black smoker fluids, and the geometry of these structures, the frequencies of the observed resonant signals are reasonable. ”

“ A radiation of definite composition occupies the interior of a cavity of temperature , and is independent of the cavity's material composition. The cavity contains an energy density for frequencies between and . Finding as a function of and poses a problem. If an electric resonator of eigenfrequency and negligible damping occupies the cavity, the time average of the resonator's energy as a function of can be calculated from the electromagnetic theory of radiation. ”

“ There is now introduced on its axis [210] a ring which has seven tubes or graduating resonators, the ring being two-thirds the diameter of the globe, the resonators three inches long and 3⁄4 inch diameter, each one to be set on the chord of B flat, which is done by sliding the small diaphragm in the tube to a point that will indicate B flat. This setting then controls the metallic displacement of the metallic combination, as also of the arms necessary to hold the ring and resonators on shaft or axis. Thus the second equation is established, both on resonation and displacement. ”

“ In the light reflected from an extended source, the ground will be of full brightness corresponding to the source, but it will be traversed by narrow dark lines. By transmitted light the ground, corresponding to general values of the obliquity, will be dark, but will be interrupted by narrow bright rings, whose position is determined by sin 1/2 (κδ) = 0. In permitting for certain directions a complete transmission in spite of a high reflecting power (e) of the surfaces, the plate acts the part of a resonator. ”

“ It is apparently also necessary for successful binaural listening that the two portions of the incident wave which enter the two receivers should be free from subsequent distortion; in particular, that the sound receivers should be as nearly as possible non-resonant for the vibrations in question. Any amplification of the sound which depends upon resonance, therefore, such as the use of Helmholtz resonators already referred to, is incompatible with efficient direction-finding by observations of phase difference. ”

“ Whenever these two conditions coexist, considerable power or activity will, of course, be necessary in the source of energy. At present they only coexist in the sun and other stars, in the electric arc, and in furnaces.
Two Circular Vibrators Sparking in sympathy.
The receiver Hertz used was chiefly a circular resonator (Fig. 6) , not a good absorber but a persistent vibrator, well adapted for picking up disturbances of precise and measurable wave length. Its mode of vibration when excited by emitter in tune with it is depicted in Fig. 2. ”

“ The combination tones thus produced in the source should have a physical existence in the air, and the amplitudes of those represented in (35) should be of the same order. The conditions assumed in this investigation are probably nearly realized in a harmonium and in a double siren of the form used by Helmholtz, and in these cases there can be no doubt that actual objective tones are produced, for they may be detected by the aid of resonators of the frequency of the tone sought for. If the tones had no existence outside_ the ear then resonators would not increase their loudness. ”

“ Just as acoustic resonance may be simple or sympathetic so electric resonance may be simple or sympathetic. Simple acoustic resonance is the direct reinforcement of a simple vibration and this condition is had when a tuning fork is mounted on a sounding box. In simple electric resonance an oscillating current of a given frequency flowing in a circuit having the proper inductance and capacitance may increase the voltage until it is several times greater than its normal value. Tuning the receptor circuits to the transmitter circuits are examples of sympathetic electric resonance. ”

“ The effects of resonance are being more and more noted by engineers and are becoming of great importance in the practical operation of apparatus of all kinds with alternating currents. A few general remarks may therefore be made concerning these effects. It is clear, that if we succeed in employing the effects of resonance practically in the operation of electric devices the return wire will, as a matter of course, become unnecessary, for the electric vibration may be conveyed with one wire just as well as, and sometimes even better than, with two. ”

“ RESISTOR.--A fixed or variable resistance unit or a group of such units. Variable resistors are also called resistance boxes and more often rheostats.
RESONANCE.-- (1) Simple resonance of sound is its increase set up by one body by the sympathetic vibration of a second body. (2) By extension the increase in the amplitude of electric oscillations when the circuit in which they surge has a natural period that is the same, or nearly the same, as the period of the first oscillation circuit.
RHEOSTAT.--A variable resistance unit. See Resistor. ”