To replace conventional mufflers on trucks and other noisy machines, a Canadian company has developed a "silencer" whose inner workings are shaped like a conch shell.
The developer, Temro of Winnipeg, Manitoba, a subsidiary of Budd Co. of Troy, Mich., contends that the device for diesel engines is up to three times as effective a sound deadener as a conventional muffler and can eliminate 75 percent of the noise from a truck's exhaust pipe.Mufflers work in two ways: by reflecting sound waves back on each other so they cancel out and by using sound-absorbing materials. Temro says its muffler, called the Cowl Silencer, uses both methods.
Stainless steel wool within the walls helps absorb sound while small holes in the spiraling walls allow waves to pass through and cancel others. Because it does not have the baffles and chambers of typical mufflers, the spiral design reduces the back pressure that can limit an engine's performance.