In noise-reduction applications, the need for a reactive muffler usually arises when transporting gas

through a duct. For sound transmission through the duct to be minimized, an acoustic suppression

device must be incorporated into the duct system. For example, in internal-combustion engines, it is

required to reduce the intake and exhaust noise to acceptable levels. This may be accomplished by

inserting a muffler in the intake and exhaust ducting to attenuate the pressure pulsations before they

reach the environment.