Interest in acoustics continues to increase. Although this branch of science was concerned primarily with the promotion of qualitative and quantitative sound transmission until a few decades ago, emphasis is currently placed also on the limitation of sound nuisance and, by extension, the setting of boundaries for permissible sound levels in places vhere people are found. This last aspect in particular is exercising more and more influence on the design of buildings and machines, and in town and country planning. In addition, sound vibrations, because of their physical characteristics, are...