Masuzawa N., Fukahori K.

Various environmental noises have been generated a lot in daily life. Recently, results of many studies on noise have been reported. Research subjects are restricted mainly in audible frequency range noises because of their effect or harm to human being. For this, since noises in ultrasonic range are inaudible, and their existence and the effects are not evident, reports on ultrasonic noise are few. However, it is considered that noises exist in not only audible frequency range but also ultrasonic frequency range. Many kinds of measurement systems for measurement of noise are marketed. However, measurement systems which can measure noises up to ultrasonic frequency range are few and expensive. Moreover, they are not suitable for the outdoor measurements. In this study, we made and used a measuring system, microphone and peripherals, to measure noises in ultrasonic range. The measuring system we made can be operated with battery and is easy to carry because it is small and simple. �@�@We measured at such places as urban road and expressway with a lot of cars where ultrasound might exist. It was found from the result that noise in ultrasonic frequency range exists in our environment.