Anti-noise devices effectiveness: physics, models, validation, how are we able to conclude on these?

摘要

During the last 30 years, numerous products have been developed in order to improve the effectiveness of anti-noise devices, including different shapes, materials, or added devices. Sometimes, these devices are presented as the best ever, clamining drastic improvmeents on existing "common designs". Some other times, one demontrates the uselessness of such or such product. Who is right, and who is wrong? What can be the method to objectively quantify the "value" of such products? Using model can be the best or the worst thing, as one can forget, or even ignore some essential parts of the physics, what can modify the interpretation of some trends. Testing devices, either in laboratory or in situ is also a difficult matter, as the conclusions are always, and only, related to the test conditions.