The author has developed a th 三 n film ther 皿 o − couple made by evaporating process in combination with a D . C . galvanometer tD function as a detector or a device for measuring intensity of sound field , The author calculated the temperature rise ef the thermo −couple assuming that the mechan 三 sm is a kind of hysteresis loss caused by the delay of alternating heat conduction between air medium and rigid surface in analogy to Dr . 」 . Saneyoshi ' s theory on the heat conduction damphlg of

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... sating gas bubbles which resonate to ultrasonic Wave in liquid. It is proved that the value of temperature rise measured by the thermo − couple is coincident w 量 th the value theoretically calculated . The te皿 perature rise is proportional to the square of the sound pressure and to the square root of the sound frequency according to this theory . The fact that this detector has the same characters is . also ascertained by this experiment . §L 緒 言