Exhaust Resonators

Noise pollution has long been a source of discontent in larger population centers. Ancient civilizations restricted travel after dark because of the distraction of street noise. As United States population centers blossomed, public sentiment over noise pollution from the increasing size of the machines that moved them was building. Exhaust systems have been around since the early days of the automobile. These early exhaust systems were similar to modern exhaust systems with long steel tubes extending from the exhaust manifold and leading to the rear of the vehicle. Back then, exhaust systems were designed more to help dissipate the heat and keep the fumes from the engine and passenger compartment. It did very little about the noise. The design of the exhaust system was based on the sound resonating principle developed by Hermann von Helmholtz in the mid-19th century. Helmholtz proved sound frequencies could be canceled out by a matching frequency within an appropriately sized chamber. This system remained more or less intact until after WWII as manufacturers were refining their production processes to increasingly tighter tolerances and with greater knowledge of sound management. By the 1960’s, pollution became a hot social issue and noise came along for the ride since it was usually generated by an engine producing toxic exhaust. In response, car manufacturers began introducing automobiles with a new device called a resonator. The resonator works in tandem with the muffler to eliminate increasingly more sound frequencies from the engine. But instead of reducing sound, the resonator’s job is to give the sound a different, more tolerable, tone. With highly sensitive sensors, today’s resonators work closely with the entire exhaust system and controlled by the engine computer for optimal exhaust system performance.