By using this method, the effects of various parameters on the performance of the exhaust muffler and a variation law are clear and all the indexes of the new muffer are improved.
The sound tranfer loss of 2 kind of muffler structures are calculated, then tested and verified on the double sound transferrer random exciting exhaust muffler testing rig.
The earplugs, made by a firm that 3M bought in 2008, were distributed to troops during the conflicts in Afghanistan and Iraq, but the servicemen claim that the noise mufflers failed to prevent a loss of hearing.