船の騒音測定法に関する考察

抄録

Recommendations about the machinery noise measurements have been lately proposed and discussed in ISO.
In this paper are discussed the several problems about the ship noise measurements according to those proposals, and this paper is based upon the results of extensive noise and vibration surveys that, over the last several years, have been made in various types of merchant-and war-ships on their trial navigations.
The results of the observations may be summarized as follows.
(1) Acceleration type vibration pickup, about 10 grams in weights, is good for solidborne noise measurements, as the load effect of the pickup and the effect of the contact surface compliance between the vibrating surface and the pickup, mounted by means of scotch tape with adhesives on both sides, are nearly negligible.
It will be desirable to adopt the acceleration levels refered to π×10^-5 cm/sec² and, if neccesary, to convert them to the velocity levels refered to 5×10^-6cm/sec.
(2) Noise level should be measured by the A weightings of sound level meters regardless of noise levels.
Noise (airborne, solidborne) analysis usualy should be made by octave band filters depend on IEC recommendation and the convertion between old and new octave band level will be made by interpolation.
Noise levels in the ship compartments and acceleration levels on the surrounding walls seem to be dispersed within several decibels.