ACOUSTIC INSULATION OF SINGLE PANEL WALLS PROVIDED BY ANALYTICAL EXPRESSIONS VERSUS THE MASS LAW

Analytical solutions are presented for the calculation of the acoustic insulation provided by an infinite single panel wall when subjected to a spatially sinusoidal harmonic line load or a point pressure load (modelled as a superposition of spatially sinusoidal harmonic line loads). The method used does not entail limiting the thickness of the layer, as the Kirchhoff or Mindlin theory requires, and fully takes into account the coupling between the fluid (air) and the solid panel. All calculations are performed in the frequency domain. Time signatures are obtained by means of inverse Fourier transforms. Special attention is given to the limitations of the simplified models, which are not able to predict dips of insulation such as that due to the coincidence effect. It has been shown that, although time results may appear complicated, the arrival of various pulses at the receivers can be understood in terms of the travelling body pulses and guided waves. Simulated results have been computed for ceramic, concrete and glass walls of different thickness, when subjected to plane, linear and spherical waves. The insulation computed was found to be highly dependent on receiver position, given the interaction between the incident wave field and the directed reflected field on the wall, when the wall is struck by a cylindrical or a spherical pulse wave.