Rattle laboratory testing of windows exposed to sonic boom excitation.

Abstract

One of the major factors contributing to the annoyance indoor listeners experiencing sonic booms is window rattle. In earlier work the authors experimentally obtained a data set of responses of a large number of different window types installed in residential houses. Several of the windows studied were removed intact from tested houses and brought to a laboratory facility for further testing. They were affixed to a massive upright stand that simulated the house wall. These windows were acoustically excited using the same portable sonic boom simulator as in the in-situ tests. The results collected during the laboratory testing showed that rattle sources depend on window construction. Main rattle mechanisms were identified. Based on the knowledge gathered, a semi-empirical rattle model was developed defining the key parameters. Vibrational response of the window subjected to sonic boom excitation was modeled as a single degree of freedom system. The ratio between window element velocity and rattle-radiated sound pressure was obtained experimentally for the laboratory tested windows. The rattle-radiated sound level in the laboratory was compared with sound pressure levels received in front of house window exposed to typical and to low booms during NASA supersonic flight testing in 2007. [Work supported by NASA.]