Sonic boom induced window rattle in indoor environments

Abstract

The perceptual environment inside homes ensonified by sonic booms consists mainly of the transmitted indoor boom sound, rattle from items in loose contact with vibrating structures, and structural vibrations that may be felt or seen. In this presentation, measurements of window rattle from a recent laboratory study conducted inside the Interior Effects Room at NASA Langley Research Center will be summarized. Low amplitude sonic booms were reproduced at the facility exterior, which induced rattle in several distressed windows that were interchanged in the facility wall. The indoor sound field, the combined transmitted boom and window rattle sound, was measured at seven microphones placed inside the test room. The “rattle only” sound was recovered by subtracting the “boom only” sound, which was computed by convolving a measured room impulse response with the exterior excitation waveform, from each microphone measurement. In total, predicted low booms from fourteen different vehicles, each at three loudness levels, ensonified forty-two different window rattle conditions. Each measurement was repeated six times in both a lively and damped room configuration. This database of 148,176 rattle measurements enabled objective comparisons of rattle produced by different aircraft, at different booms levels and for different window rattle conditions.