The Young's modulus of the 1 mil "Mylar" C polyester film was measured in a frequency range of 100 to 4000 c/s as a function of temperature, together with the study of the symptom of dependency on directions of the film. The frequency dependence of the Young's modulus has been found to be almost inappreciable. It has also been found that the values of the Young's modulus in dyne/cm^2 are 5. 2×10^<10> at 15℃ and 3. 3×10^<10> at 90℃ in the maximum direction, while 4. 2×10^<10> at 15℃ and 2. 8×10^<10> at 90℃ in the minimum direction. The variation of the Young's modulus with static tension was measured at 15℃ and 251 c/s which was found to be very small.
When an ultrasonic beam is radiated into the bloodvessel by a transducer placed on the surface of the skin, the reflected waves are produced from the blood-flow. Hence they can be detected as a kind of tone by means of a sensitive receiver. Because the intensity and the frequency character of this tone is proportional to the velocity of the blood-flow, it is possible to investigate the behavior of the blood-flow through this method. Tones are consisted of two kinds, one of them being produced by the carotid arterial system while the other produced by the limbs arterial system. The author suggests to make a diagnosis of Arterial sclerosis utilizing this method.
A sound-energy flux-meter applicable for accurate measurements is discussed. Its microphone head consists of two pressure microphones of nearly same characteristics; the voltage e_v proportional to the particle velocity v is obtained by time integration of the difference in voltage of the two microphone outputs. As the sound-energy flux density P is defined by the time average of p×v, the sound energy flux-meter must necessarily contain a multiplier such as the electronic wattmeter. The authors used a phase sensitive detector of new type as the multiplier, to construct a instrument with the accuracy of 2-3 %.