Firing of weapons or detonation of explosives are examples of Defence activities that generate impulsive noise. This noise can be dangerous for the personnel as well as annoying for people living in the neighbourhood of barracks or shooting ranges. TNO investigates the propagation of this noise, its impact on the environment, and gives advice on noise reducing measures.
TNO has developed methods to measure the intensity of the noise at the source and is able to calculate the propagation of the noise from its source to the environment and to determine its subsequent impact.
Shooting practice, using rifles and pistols, takes place in the Netherlands on shielded firing ranges with concrete shields above the firing area. This ensures that the bullets are contained within the firing range and do not ricochet off into the surroundings. TNO studies the impact of the noise of these ranges on residential areas in their vicinity and advises on measures that can be taken to reduce this impact.
The propagation of the noise in the atmosphere is closely related to the meteorological conditions and the properties of the soil; i.e. they can make the noise propagation either stronger or weaker. TNO has developed validated calculation models to determine the noise propagation across large distances. TNO's models are able to take into account the meteorological conditions in detail and therefore very precisely determine the noise propagation. Since these models can be linked to meteorological prediction models, the noise impact can be forecast up to 48 hours. Special research has been performed on heavy artillery, which produces low-frequency noise that propagates over large distances. Such type of noise is difficult to reduce. TNO has cooperated with the American Defence Ministry to study the measures that have the best chance of reducing the noise made by these weapons.
Explosion shock waves can cause buildings to vibrate and, consequently, might result in constructional damage. TNO performs measurements and model calculations for buildings to determine the likelihood of any damage.