In this paper a description of the use of simplified numerical methodologies for determining the low cut-off frequency of anechoic and hemi-anechoic chambers will be presented. The anechoic chamber has been modeled as a cavity with proper surface impedance boundary conditions. Firstly, the surface impedance is determined by means of a finite element model of the wedges in a "virtual" impedance tube for a plane wave field. Successively, both analytical and numerical procedure are used for determining the complex reflection coefficient for spherical waves at oblique incidence. Finally, a complex image source approach is used for predicting the sound field within the chamber. The methodology will be applied to the new anechoic chamber of the University of Ferrara, having volumes of 650 m3 and 800 m3 in anechoic and hemi-anechoic configurations, respectively. Results will be compared in terms of sound decays along fixed directions and surfaces pressure distributions.
Scheda prodotto non validato
Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo
|Titolo:||Numerical methodologies for predicting the low frequency behavior of anechoic chambers|
|Data di pubblicazione:||2009|
|Appare nelle tipologie:||04.2 Contributi in atti di convegno (in Volume)|