Suggested modifications to American Society of Testing Materials test method E 477

摘要

ASTM E-477 is the current standard test method used in North America for evaluating theacoustic and aerodynamic performance of duct silencers. The test method uses, at aminimum, a source chamber, a test duct (that includes a test specimen), and areverberation chamber. If testing under flow is desired, the system also requires a fanchamber that can provided quiet airflow through the test duct. The results of the testmethod yield silencer insertion loss, self-generated noise, both as a function of acousticfrequency and flow velocity, and pressure drop. There are several problems with thecurrent test method, some that are being addressed by the ASTM working group that isresponsible for the development and maintenance of this standard. This paper willhighlight the most significant problems associated with the current standard and proposemodifications to the standard that should, if adopted, improve the intra-laboratoryreproducibility of the test results.