A new method for calculating the sound energy density based on geometrical acoustics

Unlike the well-known computation of sound energy density based on the concept of sound intensity and on the assumptions of geometrical acoustics, in this paper a newcomputational scheme is developed and experimentally verified. Though keeping the basics of the geometric theory, the newmethod is based on the concept of force density in the acoustic field. It is shown that, starting from the single force contribution of each image source, the outcome of the global force acting at the receiver point is easily computed. The sound energy density evaluated with the new method differs from previous theories. As a consequence, the derived predictions of both reverberation time and sound energy level are different. The consistency of this newmethod with available experimental data is investigated and newdata are added that provide evidence in favour of the newcomputational scheme. The relation between this procedure and current formulas for reverberation time is studied and discussed, too, and an improvement of Eyring’s formula is proposed.