CPC Subgroup
F01N 1/24 by using sound-absorbing materials (F01N1/04, F01N1/06, F01N1/10, F01N1/14, F01N1/16 take precedence)
Full Title
Silencing apparatus characterised by method of silencing > by using sound-absorbing materials (F01N1/04, F01N1/06, F01N1/10, F01N1/14, F01N1/16 take precedence)