Abstract
The aim of this report on the acoustical properties of ships is to present data for the assessment of the relative importance of noise sources, noise paths and noise reduction measures in ships as far as human comfort is concerned. It is therefore a more practical parallel to a preceding report “Acoustal principles in ship design”.
The instruments used for the measurements by the Technisch Physische Dienst are described briefly. Also some information on recent trends in noise criteria is given. Noise spectra, as measured in cabins of different ships, are compared, stressing the importance of the distance between noise source (e.g. engine room or propellers) and cabin.
Results of measurements on structure-borne sound (vibrations) and on air-borne sound due to propellers or engines are compared with results obtained during excitation of parts of a ship’s structure by means of a tapping machine.
With the aid of theoretical and experimental models the various possible noise paths are identified and investigated as to their respective contributions to noise in a cabin.
The conclusions about the origins of a cabin noise may be of some value for an “engineering estimate”, as is illustrated in the last chapter. A list of references is given.
For practical reasons the report is published in two parts; part I (chapters 1, 2, 3, 9 and 10) containing introduction, information on instruments, criteria and a summary and illustration of results; part II (chapters 4, 5, 6, 7 and 8) containing the results of measurements and some theoretical considerations.
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