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Conference_programme: 17.2 - Low frequency sound insulation

Lecture: Measurement and prediction of the acoustic performance of a CLT floor in an extended frequency range

Author(s): Larsson Krister, Colebring Andreas, Glebe Dag

There is an increasing demand for bio-based and renewable materials for more sustainable buildings, and wood is therefore an attractive construction material, especially in countries with ample forest resources. The use of massive Cross Laminated Timber (CLT) in various building elements, such as floors and walls, is becoming more and more popular for example in Sweden, also thanks to its architectural benefits. However, the acoustic performance, especially at low frequencies, is a challenge. In this study, a 230 mm thick homogeneous CLT floor was tested in a laboratory in combination with various floating floors, and suspended ceilings. Because of restrictions on total construction depth the types and dimensions of the solutions were limited. While airborne sound insulation was measured down to 50 Hz, measurements of impact noise were conducted in an extended frequency range down to 20 Hz in order to evaluate the low frequency performance, which is recommended in the Swedish sound classification scheme for residential buildings in the higher sound classes. Vibration measurements at different layers in the constructions and dynamic stiffness of the resilient layers in the floating floors are used to study resonance phenomena and as input to prediction models. Measurement data were in addition used to auralize both airborne and structure borne sound through the floor to give a better understanding of the acoustic performance of the constructions for non-acousticians. The results show that the 230 mm thick CLT floor in combination with a floating floor may fulfill acoustic requirements for office buildings, while for residential buildings there is a need to improve the acoustic behavior in order to be an acceptable solution. The possibilities to achieve acceptable solutions are significantly severed with more constraints of e.g. total construction depth.

Corresponding author

Name: Dr Krister Larsson

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Country: Sweden