NOISE ATTENUATING MEASURES FOR MACHINERY ON DIESEL SHIPS

Although there has been extensive study of noise-reduction measures for cabins and engine control rooms, not much attention has hitherto been paid to noise-attenuating measures for machinery in general. The Authors give an account of a study in which the influence ratio, of noise from machinery to the noise level of a room, was investigated in several motor-ships of different types. This ratio is the most important factor to be considered when noise-attenuating measures are applied to machinery. It was found that the noise level in cabins was greatly influenced by structure-borne noise from main engines, that the level in control rooms was affected by the noise and that the level in control rooms was affected by the noise from main and auxiliary engines and from other machinery. Noise in cabins can therefore be effectively reduced by applying measures to the main engine, but, for a control room, it is necessary to apply measures to each machine in proportion to the corresponding influence ratio. More effective control of structure-borne noise from main engines is the most important aspect for a future study of noise-attenuating measures in motor-ships.