1958 年 14 巻 1 号 p. 18-24
This paper deals with a qualitative consideration of experimental results of the evaporated thermo-couple used as an intensity detector in a sound field. This special thermo-couple is made of evaporating Bi and Sb or their alloys on the mica or collodium film in a vacuum. It has been found that the electro motive force generated in a sound field is a direct current E. M. F. proportional to the square of the sound pressure. From this fact, the possibility of using the special thermo-couple as a measuring instrument of sound intensity was established. The frequency range of the thermo-couple in this experiment is from 200 to 5000 c/s. This instrument does not indicate the alternating electro motive force induced by the sound wave, so the time constant of the thermo-couple is not a serious problem. Further-more the resistance of the thermo-couple must be a stable one.