Standard Test Method for Laboratory Measurement of Acoustical Effectiveness of Ship Noise Treatments

Abstract

5.1 To fully understand the effects of a given treatment, five acoustical factors (transmission loss, acceptance, radiation efficiency, absorption, and damping) must be characterized. For example, only knowing the effect of a given treatment on transmission loss will not allow the acoustical designer or engineer to assess its impacts on propagation of vibration (among other effects), which is an important path to consider for large machinery items and propeller excitation. 5.2 It is necessary to have a common definition of acoustical performance and test procedure to determine all five acoustical factors for ship’s treatments so that the performance of different treatment types, as well as the same treatment type from different manufacturers, can be compared. 5.3 In some cases, particularly for damping treatments, the effect of the treatment will be dependent on the non-treated structure’s material and geometry and other non-acoustic factors such as environmental conditions (that is, temperature). To fully characterize a treatment it may be necessary to test a range of base constructions. For reasons of practicality, convenience, or economy, it may be sufficient to test only one to three constructions to achieve an understanding of the material performance in a range of practical situations. Additional discussion is provided in Annex A1.