Pressures inside coupled rooms subjected to sonic boom

An acoustic system of two coupled rooms subjected to sonic boom was studied numerically and experimentally. The physical dimensions of the acoustic system are small compared to the wavelength of a sonic boom signal and justify a Helmholtz resonator approach. Oscillation frequencies and damping ratios were calculated for window areas ranging from 0 to 0.6 sq/cm, room volumes ranging from about 7 cubic m to 42 cubic m and the average absorption coefficient ranging from 0 to 0.25. Pressure responses were calculated for similar conditions using sonic boom input signals with durations varying from 100 ms to 300 ms and various rise times between 0 and 0.25 times the duration. The UTLAS Travelling Wave Horn Type Sonic Boom Simulator was available for the experiments. Experiments were conducted, using window areas up to about 0.6 sq cm, and input durations between 100 ms and 300 ms. Very satisfactory agreement was achieved between analysis and experiment by using an average absorption coefficient of 0.25 for both rooms.