Resonator

[Sarah]

Anything which resounds; specifically, a vessel in the form ofa cylinder open at one end, or a hollow ball of brass with twoapertures, so contrived as to greatly intensify a musical tone by itsresonance. It is used for the study and analysis of complex sounds.

[Sonia]

An apparatus that increases the resonance of a sound, especially a hollow part of a musical instrument.

[Lanell]

a device, for example in a musical instrument, that makes sounds resonate