Vibration Absorbers It is possible to forget that in the majority of cases vibration is only considered when there is a problem. It is therefore of great practical importance to be able to reduce vibration amplitudes. We will now consider vibration absorbers. These go under various names, undamped vibration absorbers are also called detuners. Damped vibration absorbers are sometimes just called vibration absorbers. The situation shown in the adjacent animation is of great interest. When there is a sinusoidal excitation with a fixed frequency then in theory it possible to stop vibration. Since the top mass is not moving there can be no resultant force on it. The lower spring and mass are vibrating so that the exciting force is balanced by the force applied by the lower spring. As the lower spring/mass system is vibrating freely without any force applied to it and the mass to which is attached is at rest, then the lower spring/mass system is vibrating at its undamped natural frequency. We shall first consider the undamped vibration absorber.