Professor Peter Svensson (The University of Trondheim, NTNU, Norway) and Erling Nilsson (Saint-Gobain Ecophon AB / Professor at Lund University, Sweden) will each be giving a talk in a joint session on Thursday December 13th from 2 pm to 4pm. The talks will take place in Building 354, in the meeting space before the AVIL (details below).
Talk 1 (14:00-15:00)
Prof. Peter Svensson (The University of Trondheim, NTNU, Norway)
Title: Hybrid method for computing scattering, combining edge diffraction and the boundary element method.
Abstract: Scattering from a convex, rigid polyhedral object can be computed accurately and efficiently with an edge-diffraction based method, the “Edge Source Integral Equation" (ESIE). However, this approach has numerical challenges for certain radiation directions, namely those that coincide with one of the infinite planes that form the polyhedral scatterer. These numerical challenges can be avoided by using the ESIE to compute, as an intermediate step, the sound pressure at the surface of the scattering body, rather than the radiated sound pressure at the external points of interest (the field points). Subsequently, the surface sound pressure can be propagated to the external field points using the Helmholtz integral, just like in the second computation step of the boundary element method. This approach, which we term ESIEBEM, avoids the numerical challenges of the direct ESIE approach. Comparisons with reference BEM results will be presented.
Talk 2 (15:00-16:00)
Erling Nilsson (Saint-Gobain Ecophon AB / Professor at Lund University, Sweden)
Title: Room acoustics in practice.
Abstract: A common room acoustic measure in ordinary public rooms is a suspended sound absorbing ceiling. The acoustical conditions in these types of rooms not only depend on the suspended ceiling. The size and shape of the room as well as the properties of building material and the interior fittings and furniture will also affect the room acoustical conditions. As a consequence of the non-uniform distribution of the absorbing material the classical diffuse field assumption is not fulfilled. This makes the calculations of room acoustic parameters more complex. This talk addresses the effect of different factors that are of importance for the acoustical conditions in ordinary rooms with absorbent ceilings. The effect of introducing a suspended ceiling, adding furniture, adding wall panels as well as extra low frequency absorption will be exemplified based on measurements in a full scale classroom. Comparison with calculations according to Sabine's formula will be made. A calculation model adapted for the non-diffuse conditions in rooms with ceiling treatment will be briefly discussed.