A series of analysis for the zonal sound radiator was performed. In the present paper, the analysis for the zonal vibration of a sphere was developed. The directivity of radiated sound pressure and power were calculated. The radiation impedance were obtained, too. The results were compared with the data in the preceding paper on a prolate spheroid.
The statistical method of measuring the fluctuating noise, such as city noise, is proposed. Instantaneous indications of a sound level meter are recorded on a list at every five seconds. And the average level and the distribution of noise are tentatively defined from a frequency curve or integral curve of that readings. Deviation of the results can be minimized by taking a sufficient mumber of readings and smoothing operation of the data.
For the purpose of irradiading high power ultrasonic waves into various liquids in 10-30kc range, a spherical flask is suitable for obtaining efficient results. Hence, we calculated the natural frequency of liquid-filled complete spherical shells. First, we calculated the kinetic and the potential energy in the liquid and the shell when they are vibrating at the same mode of axially symmetrical surface harmonics(zonal harmonics), and then determined the frequency equation from the conditions that the sum of the both energies is constant with respect to time and that the normal velocity is continuous at the boundary surface. Numerical example for glass flasks containg water is given in the present paper. The experimental results on actual flasks at 14. 2kc agreed with the theoretical result in rough approximation.
A second quartz plate(B)was connected between grid and cathode of the vacuum tube of a Pierce oscillator circuit employing the control quartz(A)connected between plate and grid of the vacuum tube(in this experiment 42 or 6L6A). A was an oscillator quartz of high precision and low temperature coefficient, and B an x-cut transducer quartz used in the ultrasonic interferometer, both crystals being of nearly the same frequency(in this experiment 1. 43Mc/sec or 0. 47Mc/sec)with a frequency difference of several hunhred cycles per sec. This circuit worked with high sensitivity and good frequency stability for liquid interferometers, when used with plate voltage of 70〜100volts. The deviation of frequency by insertion of the transducer quartz was usually less than 100cycles/sec and always less than 0. 02% of the frequency value.
Theoretical Analysis of the circuit described in the previous paper has been performed, particularly examining the influence of the transducer quartz on the frequency of oscillation. In the first place the theory of the Pierce circuit oscillator was generalized in taking the effect of the grid current also into consideration. Then the influence of the transducer quartz on the frequency of oscillation was examined by this theory. The frequency shift to be expected theoretically in our case proved to be less than 0. 04% of the frequency value, in good accordance with the experiment.