Vibration and structure-borne sound
Vibration matters to acoustics twice. First as a source of sound: a pump or fan bolted to a building injects structure-borne power that travels through walls and floors and re-radiates as audible noise rooms away. Second as a human exposure in its own right: vibration transmitted to a standing, seated or hand-gripping person is measured, weighted and limited much like noise, with its own metrics and legal action values.
The structure-borne sources pages follow the source chain in order. The frequency-response-function family of ISO 7626 (receptance, mobility, accelerance) is the vocabulary; the transfer stiffness of ISO 10846 characterises the resilient elements that interrupt the path; ISO/TS 7849 estimates the airborne power a vibrating surface radiates directly; EN 15657 measures the structure-borne power a machine injects into a reception plate; and EN 12354-5 assembles all of it into the sound pressure level predicted in a receiving room. That final prediction is also where this section hands over to the sound insulation models of the buildings section.
The human vibration pages share the measurement philosophy of a sound level meter, applied to acceleration: frequency weightings that reflect body response, running and integrated averages, and dose quantities compared against the action and limit values of Directive 2002/44/EC, plus the dedicated spinal-response model for vibration containing repeated shocks.
Start with Mechanical mobility and the FRF family if you care about machines and buildings, or with Human Vibration if you care about people.
From FRF vocabulary to the predicted level in a receiving room.
- Mechanical mobility and the FRF family (ISO 7626-1): receptance, mobility and accelerance with their reciprocals, and the SDOF reference resonator.
- Bending-wave transmission at plate junctions (Cremer/Craik/Hopkins): the frequency-independent wave-approach coefficients for rigid X, T, L and in-line junctions, their angular average and the derived coupling loss factor and Kij.
- Transfer stiffness of resilient elements (ISO 10846): the dynamic transfer stiffness of vibration isolators by the direct and indirect methods.
- Sound power from surface vibration (ISO/TS 7849): radiated airborne power from surface velocity and a radiation factor.
- Structure-borne sound power of equipment (EN 15657): the reception-plate method and the plate-independent source quantities.
- Installed structure-borne sound (EN 12354-5): the receiving-room sound pressure level predicted from source and receiver mobilities.
Vibration transmitted to the human body, from daily exposure to spinal injury risk.
- Human Vibration: whole-body and hand-arm weightings (ISO 8041-1), r.m.s. and dose measures (ISO 2631-1), daily exposure A(8) (ISO 5349) and the Directive 2002/44/EC values.
- Multiple-shock whole-body vibration (ISO 2631-5): the spinal-response model and the probability of lumbar injury for vibration containing multiple shocks.