Time-domain effects of rigid sphere scattering on measurement of transient plane waves.

Transient waves, like all other acoustic waves, will diffract around solid objects, such as measurement instrumentation. A derivation of an impulse response function on the surface of a rigid sphere, based on linear, classical scattering theory, is presented. The theoretical impulse response function is validated using an experiment with blast noise. An application of the impulse response function to a rocket noise measurement is discussed. The impulse response function shows that the presence of the rigid sphere significantly affects the measurement and estimation of rocket-noise waveforms, power spectral densities, and statistical measures.