The US Patent for an ‘Exhaust muffler for engines’ was awarded to Milton O. Reeves and Marshall T. Reeves of Columbus, Indiana of the Reeves Pulley Company on 11 May 1897. US Patent Office application № 582485 states that they “have invented certain new and useful Improvements in Exhaust-Mufflers for engines”.
Trade-off between power increase and noise reduction
When the flow of exhaust gases from the engine to the atmosphere is obstructed to any degree, back pressure arises and the engine's efficiency, and therefore power, is reduced. Performance-oriented mufflers and exhaust systems thus strive to minimize back pressure by employing numerous technologies and methods to attenuate the sound. For the majority of such systems, however, the general rule of “more power, more noise” applies. Several such exhaust systems that utilize various designs and construction methods:
Vector muffler - for larger diesel trucks, uses many concentric cones, or for performance automotive applications, using angled baffles to cause exhaust impulses to cancel each other out.
Spiral baffle muffler - for regular cars, uses a spiral-shaped baffle system
Aero turbine muffler - creates partial vacuums at carefully spaced out time intervals to create negative back pressure, effectively ‘sucking’ the exhaust out of the combustion cylinders