Acoustic properties of wood
Wood is a light material, so as such its sound insulation performance is not particularly good. Neither does a thick, dense-surfaced and smooth wooden structure dampen sound particularly well, so wood alone is not a good absorption material. Wood conducts sound better in the longitudinal direction of the grain than perpendicular to it. A dense wooden structure reflects sound, and can easily be made into surfaces that channel sound reflections. This property is utilised, for example, in musical instruments and concert halls.
A sufficient level of sound insulation in wooden buildings can usually be achieved structurally by using multi-layered constructions. By positioning porous absorption material behind the board or panelling in addition to an air gap, for example a layer of thermal insulation, a so-called board resonator is formed which, when it vibrates, effectively dampens low sounds that are problematic for light structures. Furthermore, by making wooden battening or by making holes in wooden surfaces, a perforated resonator can be created that also efficiently dampens medium-to-high-pitched sounds.
In multi-storey wooden buildings, the means of controlling sound insulation (separate frames, sound stops) are challenging, because they are contrary to how structural rigidity is achieved (reinforcement, joints, continuous structures). The footstep insulation of wooden floors can be improved by increasing the mass of the floor, for example using a concrete cast on the surface or so-called floating surface tiles on top of a flexible layer on the upper surface of the floor.