The influence of different material properties of straw on the building acoustic performance of lightweight wall constructions

Abstract

In the presented research, straw as building material, is used as absorptive material in metal stud walls and timber frame constructions. The results of building acoustic measurements are used to quantify the acoustic potential of straw in those wall constructions. The influence of parameters like density, dynamic stiffness and air flow resistivity of straw on the measured sound reduction index is discussed. Especially the density and the dynamic stiffness, are important material parameters to achieve a high sound reduction index of the wall constructions. An increase of the dynamic stiffness of the straw, results in a higher mass-spring-mass resonance frequency and a better mechanical coupling of the wall sheets. This can lead to a reduction of the sound reduction index up to 19 dB of the investigated double wall. For the timber frame wall, the sound reduction index including the spectrum-weighting value (Rw+Ctr) varied between 42dB and 46dB in dependence of the dynamic stiffness of the blow in straw. The results show that the building acoustic performance of wall constructions with straw is comparable to the performance of already on the market established wall constructions, if the material properties of straw are optimized.