Vibration Isolation is an important factor when trying to reduce structure borne noise. Vibrations travel through the structure which is then responsible for structure borne noise. Structural vibrations excite the air and cause structure borne noise. We follow the following strategies for vibration Isolation:
Rotating Unbalance: Most machinery contain motors or some form or rotary devices. Mass unbalance in these devices is a cause of vibrations. Mass balancing can help reduce vibrations in these scenarios.
Fan Noise: Fan noise can be reduced using various strategies. One strategy is to use bell shaped inlets and outlets and having circular shield around the blades
This can be achieved with the help of a tuned mass damper, spring isolators or spring/damper isolators. These isolators are usually coil springs or viscoelastic materials.
This is more expensive and advanced technique used when isolation at the source and passive isolation strategies are not feasible. A sensor measures the displacement of the vibrating equipment and this signal is fed to a control system which controls an actuator or actuators which then apply a cancelling signal to the vibrating equipment.