Air compressors are noisy machines. The two most commonly used ways to quiet them down are to locate the air intake outside (not good for the neighbors) or to build some type of enclosure with sound deadening material inside; that usually causes overheating problems due to poor circulation. The best solution is to construct a silencer that uses the same principles as a gun silencer. But isn't that illegal? Only if you use it on a gun. We're using it on an air compressor. Still, this topic seems to be controversial, mostly by people who have a bury-your-head-in-the-sand approach to security and safety. Here are the materials: Pipe the same size the air compressor port will use, 16"-18" long. Some exhaust pipe, the same length as the other pipe. Some washers you have to make with a hole saw, enough to put one on each end and one every 1-1/2" that will fit around the air compressor intake port pipe and fit inside the exhaust pipe. Steel wool to fit betwe...