A longitudinal-longitudinal vibration energy concentrator/divider, which has been devised by Ito et al. and is called "L-L type resonator", has such a construction that two half-wave-resonant (longitudinal mode) bars are crossed at their nodal portion of vidrational displace-ment. It is an epoch-makingly useful devise in the field of ultrasonic power applications because of its capability to concentrate the vibrational energy from plural sources into a single load or vice versa. Among several variations of those resonators (such as R-Ltype or L-L-L type etc. ), the authors took up an elemental L-L type resonator in this paper and analysed it, first, by means of coupled-vibration-theory to obtain its qualitative characteristics, and then analysed by means of finite-element-method in order to check the assumptions employed in the former analysis and to obtain quantitative values. From these studies, the analysis based on the coupled-vibration-theory is shown to be valid in qualitative sense, and the design charts of the resonators point-symmetrical with respect to its center are given. At first, the authors assumed that the vibrational displacement (u, v) of the arbitrary point (x, y) in the resonator can be expressed by eq. (1). The generalized equation of motion is given by eq. (2), which is a two dimensional eigenvalue equation in generalized form, and s_&ltij&gt and m_&ltij&gt are the coefficients given in eq. (3). Coupling factor k is defined as eq. (4). These s_&ltij&gt and m_&ltij&gt are given as eq. (7) and (8) under the assumption of two-dimensional plane-stress condition. Eq. (2) can be written as eq. (9) which is the standard expression of two-dimensional eigenvalue equation. Resonant condition of the system is given by eq. (10). The resonant frequencies f_&lt0S&gt are given by eq. (12) or eq. (13), or found in Fig. 3. Amplitude ratios for both arm ends are given by eq. (15) or (16). The product of the two respective ratios of the first and the second mode is given by eq. (17), which is always negative. By examining the sinse of the double-sign contained in eq. (16), it is found that the amplitude ratio of the first mode is negative and the second mode positive. Both ratios can be expressed as eq. (19) and are shown in Fig. 5 in normalized from. Form this analysis, coupling factor is given by eq. (14), which suggests that it is proportional to Poisson's ratio of the material employed. This relation is confirmed by the results of finite-element-analyses. Analysis described here, based on the coupled-vibration-theory, has a deficiency in that the vibrational displacement is assumed as eq. (1), which means the neglecting of the shearing stresses. The authors examined this assumption by finite-element-method, and clarified that the neglection of the shearing stresses can be permitted for the first mode, but it shouldn't be made for the second mode. For the finite-element analysis, a quarter of the resonator, as shown in Fig. 7, was analysed as a two-dimensional plane-stress eigenvalue problem by the program "FEM23". This program uses triangular-elements with three nodal points for an element and first order polynomial function as trial function. Main results are shown in Figs. 8 to 11. Comparisons with the experimental values are given in Table 1. Charts for the design of resonators point-symmetrical with respect to its center are shown in Figs. 12 and 13. Fig. 14 shows a designed example.

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The directivity characteristics and the gains are computed for the oil-filled-tube underwater transmitter and compared with experiments. It is ascertained that Hansen-Woodyard's condition (Eq. (16)) giving the optimum Iength of dielectric-rod antenna is also valid for the oil-filled-tube transmitter. Theoretical values of the directional gain G_&ltd0&gt are obtained by numerical integration of Eq. (11) using a digital computer, substituting D_k(θ) from Eq. (8). In this equation, D_&lt1k&gt(θ) means the directivity characteristic of the tube-section according to Kirchhoff's formula (Eq. (6)) and D_2(θ) the directivity due to the endfire-arrangement (Eq-(5)). Computed values of G_d0 are shown in Fig. 4 (f=21. 5 kHz), Fig. 5 (f=24. 2 kHz) and Fig. 6 (f=33. 5 kHz). Fig. 10 shows the comparison between the theoretical and experimental values of G_&ltd0&gt. Although the measurements are somewhat lower than theoretical results, the location of the maxima are in good agreements, (G_&ltd0&gt)_max increasing ca. 9 dB by attaching the "oil-filled-tube". Fig. 15 shows the comparison between the theory and measurement for the optimumtube length (L_0). Although the experimental points are slightly higher than the calculation, the general agreement shows the applicabilty of Hansen-woodyard's condition. Also the electromechanical efficency η is measured for evaluating the over-all effect of the oil-filled-tube (see Fig. 16). The observed ca. 20% increase in η by attachment of the oil-tube indicates a further advantage of this arrangement.

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This article concerns a new ultrasonic intensity standard in water, which makes use of the acoustic radiation force on a super duralumin sphere and covers the range of frequency from about 0. 2 to l0 MHz. The radiation force on a sphere of radius a placed freely in a plane progressive sound field is expressed by Eq. (2), where E is the mean energy density in the field and Y_p the radiation force function of the sphere. In the radiation force method of acoustic-intensity measurement, the mean energy density or the local intensity is determined by the measured radiation force and the calculated radiation force function. Y_p was computed from the authors' thory (1969) for a sphere of super duralumin (of physical constants listed in Table 1) as a function of ka, as shown in Fig. 2, k being the wave number in water. Experiments were made on various super duralumin spheres of 3, 4 and 5 mm in diameter suspended by a bifilar arrangement at 470-2250 kHz in an unechoic water tank of 50×80×60 cm^3 in volume. It was proved that in case of small values of ka, the absolute magnitude of acoustic-intensity for the super duralumin sphere was just the same as that for a stainless steel sphere so far used (Fig. 4). and in the range of ka over about 10, the experimental ka-dependence of Y_p agreed almost well with the theoretical one, but with minute discrepancy attributed to the errors in the values of the longitudinal and transversal wave velocities the spheres(Fig. 5-8). As is expected from consideration on the physical constants, super duralumin is one the metals that show the most flat Y_p-Ka curve (except beryllium, which hardly grinds into a ball), and is thus superior to stainless steel as the target metal in the radiation force method. The former gives a more accurate value of intensity than the latter especially in the range of large ka.

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According to the recent progress of integrated circuit technology, it has become easy to use active elements for a telephone speech circuit. Instead of the carbon transmitter used up to this time, the combination of a stable, small, light weight, reciprocal type transmitter and a sending amplifier will be used still more. The telephone speech circuit is fed electric power from the telephone office. So it is difficult to suply sufficient bias voltage to the amplifier. Then its circuit design has to be done carefully based on the knowledge about the relation of input-output nonlinearity of the circuit to the transmission performance. It is a disadvantage of the carbon transmitter that the response and speech resistance are rather unstable. And the carbon transmitter is not suitable for miniaturization. However, the nonlinearity of its response improves receiving AEN. But the said reciprocal type transmitter has not such characteristic. It must be studied to realize the nonlinear characteristic at the part of the sending amplifier circuit. Problems mentioned above are investigated in this paper. The detection level measurements of saturated distortion on telephone transmission are made. The distortion characteristics are shown in Fig. 3 and the results of measurements are shown in Fig. 4. The curve of both input and output band limitation in Fig. 4 shows the detection level in the telephone transmission performance. Using this result, the proper design parameter level of the amplifier can be decided, when the saturation characteristics of the amplifier and the output peak to peak voltage which corresponds to the prescribed sending transmission level are given. The effects of center clipping distortion on the detectability of sound are measured by the Thurston's psychometric scale and opinion test. Fig. 10 shows the relation between the psychometric scale and the clipping level which is defined by Eq. (1). From these results the center clipping distortion is allowed up to the clipping level of 0. 3 dB in the telephone transmission performance. To reduce the room noise through a telephone side tone path, it is investigated to use a sending amplifier with slight center clipping characteristics. The relation of the clipping level to the degree of receiving AEN improvement and sending AEN detrioration is measured, Fig. 16 shows a case of the total AEN improvement value. This value is 3 to 4 dB within the permitted clipping level, when the AEN is rather bad (27 to 28 dB) and the line loss is 6 dB.

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The evaluation of vibratory sensibility should be performed by a physical measurement which also relates to the subjective evaluation. It is necessary to find a new method of phsical measurement. This paper presents psychological and physical experiments carried out by using a vibrometer as an acoustical calibration apparatus. The vibration threshold value measurements of were made using sine waves of 30-700 Hz triangular, and saw-toothed waves of 30-300 Hz and square waves of 30-80 Hz. Ten test subjects were kept seated. A portion (about 80 mm^2) of the vibrator is in contact with the skin. The Square wave has a difference of 7, 9 dB at 80 Hz and the difference becomes 12. 3 dB at a lower frequency (30Hz) as compared with a sine wave. This has also been proved physiologically by the impulse rate of a stimulus given directly to the tactile receptor; it implies that a steeper stimulus has a higher threshold value. In the present paper the quantification of vibratory sensitivity is attempted, and it is shown that a potential variation of a few μV can be picked up by applying vibratory stimulus to the skin, which at the same time is used as reference signal to a lock-in amplifier, and detecting the same frequency components of electric signal generated from a living body by the stimulus, and that cutaneous sensetion can be therefore quantified as a small amount of potential variation. In order to observe the corresponding electric signal, the subjects were placed inside a shielded room and provided with Ag-AgCl electrodes at two points on their skin. In the measurements, the calibration of the electric signal observation portion was made with a 10μV sine-wave input, and that of the final detection part with a cathode-ray oscilloscope and a photocoder Owing to the size and shape of the electrodes, they were placed around the wrist of the subjects. The two electrodes were spaced apart at 50 mm, but variation of the separation at 30-40 mm exerted no effect on the electric signal. A curve was plotted by taking the stimulus level on the horizontal axis and the potential variation or strengh evaluation on the vertical axis, then it was found that there is nearly a linear relation. Furthermore in the experiment was measured the generating potential of each finger to which vibratory stimulus was added. The generating potential and the vibration threshold value are different according to the subject, but the tendency is almost same. The subject who shows a high potential has a low vibration threshold value, and the subject who shows a low potential has a high vibration threshold value. The results obtained from the experiments are as follows: (1) Vibratory sensation can be quantified as generating potential in the living body, though it has so far been measured only psychologically. (2) It may be possible to acquire more information by using square, triangular and saw-toothed waves than just a sine wave. (3) Exponent n involved in the Stevens' power law may be put as 1 for the vibratory sersation and constant k may be put as 0. 25 to 1. 4 at 40 to 200 Hz. (4) Each finger shows a remarkable potential variation at low frequencies and little vaiation at high frequencies. This paper deals with vibratory sensation only. It is a matter of course that it should be attempted to quantify other sensations.

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