A resonator is a device or system that exhibits resonance or resonant behavior, meaning it naturally oscillates with greater amplitude at some frequencies, called resonant frequencies, than at other frequencies. The term resonator is most often used for a homogeneous object in which vibrations travel as waves, at an approximately constant velocity, bouncing back and forth between the sides of the resonator. The material of the resonator, through which the waves flow, can be viewed as being made of millions of coupled moving parts (such as atoms), and therefore, they can have millions of resonant frequencies, although only a few may be used in practical resonators.

Resonators can be found in various applications, including musical instruments, radio and microwave circuits, and exhaust systems in vehicles. In the context of exhaust systems, a resonator is a part of the system that is vital to keeping the sounds coming from the vehicle at a reasonable level. It is located before the muffler and assists the mufflers objective of reducing a vehicles noise. The resonator and muffler work together to alter and reduce wavelengths produced from the engine before they exit the vehicle. The primary purpose of a resonator is to change the engine sound before it reaches the muffler for a final decibel reduction.

In summary, a resonator is a device or system that exhibits resonant behavior, meaning it naturally oscillates with greater amplitude at some frequencies than at others. It can be found in various applications, including musical instruments, radio and microwave circuits, and exhaust systems in vehicles. In the context of exhaust systems, a resonator is a part of the system that assists the mufflers objective of reducing a vehicles noise.