Numerical estimation of acoustic properties in enclosures of simple shape

A 2-D model of a rectangular room with an open window is studied. In such a room the acoustic field is not diffuse even for high frequencies. Instead, it displays modal properties in the whole frequency band. For high frequency some modes have a high Q-factor, and thus the solution of a harmonic excitation problem has a rapid and unpredictable dependence on frequency. To suppress this dependence, a procedure of averaging in the frequency domain is proposed. An algorithm of calculation of reverberation time is described.