Forced (Driven) Vibration

Getting they system to vibrate at any single mode of vibration requires exciting, or driving the system at the desired mode.

See Dan Russell's site: The forced harmonic oscillator

When a simple harmonic oscillator is driven by an external force $F(t)$, the equation of motion becomes

$$m\ddot{x} + R\dot{x} + Kx = F(t).$$

The driving force may have harmonic time dependence, it may be impulsive, or it can be a random function of time (noise).