Noise protection is another criterion determining the quality of feelings and comfort that accompany the use of the building. Studies show that exposure to too high noise levels leads to problems with concentration, irritability, stress, high blood pressure and even permanent hearing loss. In the light of these data, regardless of the type of building and the structure of its partitions, the building should provide sound insulation in accordance with the applicable provisions of the construction law. The basic function of the building’s acoustic insulation is to protect users against unacceptable noise pollution and to ensure a minimum of intimacy and peace. The implementation of this function takes place both through the appropriate layered structure of all building partitions and the way they are connected, as well as through a deliberate layout of the internal rooms. Rooms that are supposed to show increased anti-noise protection should not be located directly in the vicinity of noisy rooms. The layout of rooms, taking into account the target nature of their use in combination with appropriate construction and material solutions, should reduce the perceived noise level and reduce the sound propagation path. In construction, acoustic construction is considered the most important acoustics section, which is characterized by sources of noise occurring in building constructions, describes acoustic properties of building materials, principles of noise propagation and defines methods of anti-noise and anti-vibration protection. In general, sound insulation in construction refers to the following sound sources: – from the external environment (protection against sound emission), – from the interior of the building (protection against sound emission), – inside the building between neighboring rooms, eg a living room and a study room. The degree of protection against noise depends mainly on the surface mass, tightness and thickness of the barrier and the frequency of the sound wave acting. Conventional constructions based on a wooden frame are much lighter than single or double-layer massive walls made of, for example, concrete. This situation mainly concerns wooden constructions filled with light thermal insulation made of mineral fibers or polyurethane foam and lightweight polystyrene boards. Therefore, “classic” framework constructions are very often identified with insufficient sound insulation. However, it should be emphasized that in the case of a proper design and implementation of the layered system, even very light frame baffles meet the requirements of the construction law in terms of protection against noise. Thermal insulation materials made of wood fibers belong to the group of products with high bulk density, bringing the desired surface mass to the wooden structure. For example, the density of façade panels or over-rafter boards made of wet wood fibers is as much as 270 kg / m3, which is eighteen times more than the weight of a standard expanded polystyrene board and twice as high as the density of a hard mineral fiber facade. Covering the outside of the wooden frame structure with such a massive slab greatly increases the surface mass of the entire partition, leading to a really noticeable improvement in acoustic insulation. The specific mass of heat-insulating mats made of wood fibers (50/60 kg / m3), filling the space between the structural elements of the building, is also greater than the weight of commonly used wools and mats made of glass, mineral fibers or polyurethane foams. Detailed comparison of the density of thermal insulation materials used in frame building.
The mats and boards of wood fibers have a significantly higher bulk density in comparison to other thermal insulation materials commonly used in frame building. It is worth adding that density alone is not the only factor that defines the acoustic properties of construction products. Particular attention should be paid to the arrangement of porosity (fiberisation), dynamic stiffness and air flow resistance in the design of baffles. The best acoustic properties are obtained when using porous materials with the largest possible surface mass, low dynamic stiffness and high air flow resistance. Heat insulation façade, façade and post-mortar panels made of wood fibers are characterized by an extremely favorable ratio of the following values: open porous structure, very high density (about 260 kg / m3), low dynamic rigidity s ≤ 50 MN / m³ and relatively high air flow resistance AF ≥ 100 kPa • s / m³. As a result, when implementing this type of solutions into wooden structures, it becomes possible to obtain very good acoustic insulation.