LAUSR

The ASTM standard E90 defines the measurement of transmission loss, equivalent to the sound reduction index defined in ISO 10140. ASTM E90 and ISO 10140 specify requirements for the laboratory, the test procedure and conditions, and for preparation and mounting of the specimen under test. Despite the strict requirements in ISO 10140 and the somewhat less strict requirements in ASTM E90, transmission loss results for nominally identical specimens often vary if measured in different laboratories, and sometimes even if measured again in the same laboratory. In practice, there are many factors that affect the repeatability or reproducibility of a transmission loss test for a given specimen. This presentation will not attempt to systematically cover all different sources of uncertainty, but instead will highlight some practical issues commonly encountered in laboratory transmission loss tests. Examples will be presented for a number of issues, including the effect of leakage through the specimen under test, th...