Analysis of active noise ocntrol in a free space

摘要

At low frequencies,sound radiation by a primiary nosie soure in a free space may be attenuated by using two active nosie control strategies: (1) minimisation of totla power flow from nosie sources,and (2) minimuisaitn f local sound pressure.When the primiary and secondary sucres ar very cloase,significant glocal attenuation fothe sound field can be realised by the first strategy.If the primarly and secondary surces are far apart ,minimisaiton of the sound pressure at one or multiple locations by using one or multiple secondary sources seems to be practical.