Research on a Noise Control Device : 1st Report, Fundamental Principle of the Device

This study is concerned with a newly developed facility for controlling noise propagation and thereby producing a wide region of reduced sound power, which is expected to be effective to alleviate railroad noise, highway noise, machine noise etc.. The mechanism of noise reduction by this device is destructive sound wave interference between refractive sound waves propagating through multiple passages of different lengths eqipped with the device and direct propagation sound waves. In this paper, the structure and principle of the facility are described and the technical data for practical application are collected.