Forsknings områden

Flanking transmission of lightweight floors

New building systems are often lightweight in character, with wooden or thin-walled metal joists. An often-noticed weakness in these types of constructions is the poor sound insulation. Without an acceptable sound insulation, these building systems cannot be used in practice. One of the diffi­culties when designing the system is to handle the flanking trans­mission, i.e., when the sound passes through the struc­ture in other paths than the direct one (via junctions). In connection to lightweight buil­ding tech­niques, the junctions can be designed in a number of ways, and it is therefore impor­tant to have the theoretical tool to predict the structure borne sound trans­mission loss of the junc­tions. Measure­ments, that are expensive to perform, can then be made on the design alter­natives that seem most promising. The existing prediction methods often used in building acous­tics are not well suited for lightweight structures; they cannot handle periodicity. In this pro­ject a novel predication model is therefore under develop­ment. The prediction model will be able to handle details in the building structure, but also able to handle uncertainties in the material and geometrical properties of the structure.

Qualification of the sound diffusion in rooms

The aim of this project is to develop a laboratory method for measuring the diffusing effect of non-absorbent objects in rooms with ceiling absorbers. The diffusing effect is quantified in a measure called equivalent scattering absorption area A_sc.