In active methods of noise reduction noise is compensated with sounds produced by additional sources. The methods can be used to reduce both sound power emitted by an acoustic radiator and sound pressure level in a sound field. The number of application of these methods is growing. The selected practical applications are discussed by the author.
Katowice Province is one of the areas in Poland where excessive exposure to noise occurs. It is produced by excessive urbanization, high density of outdated industry, and a transport infrastructure which has not been modernized for a long time. Noise levels exceed permissible standards and are increasing. Noise abatement measures should be based on an acoustic plan of the area. The article presents guidelines for preparation of such a plan and also study results.
Robert Koch, a German Nobel Prize winner, said a remarkable statement a century ago: „Time will come when the man will curb noise as he fights cholera and plague today“. Above 40% Poland’s population live exposed to noise above permissible levels. In other countries situation is similar. It can be supposed that the Koch’s statement is about to come true. The article provides a sufficient number of arguments which justify such a standpoint.
Omówiono niektóre problemy zmienności poziomu dźwięku ciągników w kontekście różnic w obrębie danego typu. Wykazano, że przenoszenie wyników atestacji pojedynczych egzemplarzy wiąże się z ryzykiem popełnienia błędu przy przewidywaniu ekspozycji operatorów na hałas.