Finally, in the micropolis corners you can see ring resonators, which are a conventional (non photonic-crystal) way to achieve a resonant cavity for use in channel-drop filters, etcetera.
The external inspirator is available to drive the resonator to produce traveling wave.Under resonant frequency the distortion of resonator reached a peak.
To study the animals' roars, the team measured the volume of a howler bone in their throats which act like a resonator, the larger that bone, the deeper that voice.