Resonance

When a system with a natural vibrating frequency is stimulated by an outside force of the same frequency, the system can be set in a motion called vibration (see sympathetic vibration). As the frequency of the stimulus closely approaches that of the system, oscillation occurs, which reaches a maximum amplitude at the natural resonant frequency.

Resonance can occur in any vibrating system, including electrical circuits, the sound boxes of musical instruments, rooms (see eigenton), the cavities of the human body, including the vocal tract (see formant, vowel), and other objects (see resonator). It can be regarded as a type of natural amplification in that the transfer of acoustic energy is made more efficient, as opposed to an electroacoustic amplifier where energy is added to the system.

See: Acoustic Feedback, Frequency Response, Helmholtz Resonator, Resonance Curve, Soundboard, Standing Waves, Volume. Compare: Acoustic Radiation, Attenuation, Damping, Flat, Reverberation.