Innovative acoustical design for the multi-storey wooden buildings of the future

The wood building technology has historically had major problems with poor impact sound insulation at low frequencies caused by normal walking.

A series of research projects have shown that frequencies as low as 25-50 Hz, are of importance for the experience although sound insulation is evaluated for frequencies from 50 or 100 Hz upwards according to present standards.To design modern wooden house to withstand such low frequencies is a true challenge.

At present, no relevant method exists to attenuate low-frequency sound and vibrations in a wooden building satisfactorily. It is therefore needed to look beyond traditional solutions and focus upon alternatives –such as metamaterials. A metamaterial is a periodic microstructure integrated into a macrostructure.

Specially designed resonators can be applied to both structural vibrational waves and to airborne sound waves, resonators that are able to "consume" the energy instead of allowing it to be transmitted further in the building.

The idea is to integrate such resonators into a floor.Another idea that will be evaluated is to improve CLT floors acoustically via elastic glues.

This will lead to a reduced need of complementary material like e.g. concrete, gypsum and mineral wool.If succeeded, the potential for the production of wooden-based multi-family houses will increases which in turn leads to positive effects regarding a sustainable society as well as the residential environment, including health effects.