On the Reduction of Excessive Noise in Ventilation (Report 1)

Abstract

General excessive noises are frequently discussed lately in Japan. It seems also to be an important problem of the outfitting works to improve the living condition of a ship. The noise in ventilation is considered to be an excessive noise in a ship, and in this paper we report an investigation that to what extent such excessive noise in the duct could be attenuated. The experiments were made on various cases such as bent ducts, branched ducts, and straight and bent ducts both with interior sound absorbing material. As a result we recognized that further sound absorbent method was necessary for low frequency sound. Therefore we added further experiment on a few ducts with interior perforated panel to attenuate the low frequency sound.