For noise control in machineries, many a times a lined enclosure is placed around a machine to reduce the radiated noise. Enclosures are used around IC engines, gen­erator sets, compressors, blowers, punching press, etc. The walls of the enclosures are usually made out of thick steel sheets and are lined with sound absorbing materi­als of a certain thickness, which can withstand high temperature. Once enclosures are put around the machine, the temperature inside the enclosure increases which may affect the components of the machinery in particular the lubricants, which are used in bearings, etc. Thus usually enclosures for machines, which run continu­ously are provided with some sort of inlet air and exhaust airports. Since the ports on the enclosures have openings, it is recommended that an inline inlet and exhaust silencer is provided at the ports for bringing in fresh air and expelling out the warm air. Sometimes in few applications when the exhaust ports are not available cooling arrangement of the inlet air by a chiller is made. The inlet and exhaust silencers in such enclosure are of the dissipative type with jute-based lined ducts. Figure 6.25 shows a view of an IC engine-dynamometer setup covered by a perforated faced 50 mm jute fiber lined enclosure. The noise in the test cell reduced by around 10 dB by using such a jute-lined enclosure.