Resonator (noun)

1. A device or material that resonates, vibrates or amplifies sound or electromagnetic waves.
2. A device that produces or amplifies sound by vibrating in response to an incoming sound or electromagnetic wave.

Origin:

From the verb resonate, meaning "to produce or be filled with a deep, full, reverberating sound".

Examples:

1. The guitar's resonator amplifies the sound of the strings.
2. The resonator of the microphone improved the sound quality.
3. The resonator in the radio receiver improves the signal reception.
4. The resonator in the laser is responsible for the laser output.
5. The trumpet's resonator helps to produce a louder sound.