---
title: "Vibration and structure-borne sound"
description: "Vibration as a source of building noise and as a human exposure: the FRF vocabulary (ISO 7626), isolator transfer stiffness (ISO 10846), sound power from surface vibration (ISO/TS 7849), the EN 15657 and EN 12354-5 equipment chain, and the ISO 2631 and ISO 5349 human-vibration metrics."
---

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](/phonometry/guides/sections/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](/phonometry/guides/mechanical-mobility/)
if you care about machines and buildings, or with
[Human Vibration](/phonometry/guides/human-vibration/) if you care about
people.

## [Structure-borne sources](/phonometry/guides/sections/structure-borne/)

From FRF vocabulary to the predicted level in a receiving room.

- [Mechanical mobility and the FRF family (ISO 7626-1)](/phonometry/guides/mechanical-mobility/):
  receptance, mobility and accelerance with their reciprocals, and the SDOF
  reference resonator.
- [Bending-wave transmission at plate junctions (Cremer/Craik/Hopkins)](/phonometry/guides/junction-transmission/):
  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)](/phonometry/guides/transfer-stiffness/):
  the dynamic transfer stiffness of vibration isolators by the direct and
  indirect methods.
- [Sound power from surface vibration (ISO/TS 7849)](/phonometry/guides/vibration-sound-power/):
  radiated airborne power from surface velocity and a radiation factor.
- [Structure-borne sound power of equipment (EN 15657)](/phonometry/guides/structure-borne-power/):
  the reception-plate method and the plate-independent source quantities.
- [Installed structure-borne sound (EN 12354-5)](/phonometry/guides/installed-structure-borne/):
  the receiving-room sound pressure level predicted from source and receiver
  mobilities.

## [Human vibration](/phonometry/guides/sections/human-vibration/)

Vibration transmitted to the human body, from daily exposure to spinal injury
risk.

- [Human Vibration](/phonometry/guides/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)](/phonometry/guides/multiple-shock-vibration/):
  the spinal-response model and the probability of lumbar injury for vibration
  containing multiple shocks.
