A scale model experiment for the study of sound propagation in urban areas

A 1:50 scale model experiment for the study of sound propagation in streets is developed. Special interest is focused on the realization of the scale model in order to reproduce fundamental physical phenomena in streets such as multiple reflections and diffuse-scattering by façade irregularities. Acoustic measurements in the model are achieved using a spark discharge sound source with high level, very good reproducibility and broad band spectra. Digital processing of the measured signals in the scale model are especially developed, first to compensate the excess of atmospheric attenuation in the scale model in relation to the atmospheric attenuation in the full scale model, then, to extend the sound decay of the impulse responses beyond the noise level. The sound attenuation and the reverberation measured in the scale model are compared with real measurements in a street. The validity range of the model experiment is then discussed.