Last edited 25 May 2021

Impact sound

Sound is transmitted in buildings by both air-borne sound and structure-borne sound.

Impact sound (or impact noise) is a form of structure-borne sound that occurs when an object impacts on another, resulting in the generation and transmission of sound. The structural vibration caused by the impact results in sound being radiated from an adjacent vibrating surface. NB structure-borne sound may also be generated by vibrating sources rather than impact sources.

A typical example of an impact sound is footsteps on a floor resulting in sound being transmitted through the floor construction and heard in the space below. Impact sound can travel through solid structures and through cavities.

Impact sound can be a form of noise nuisance, particularly in dwellings, and can contribute to health problems, such as:

The occurrence of impact sound is dependent on a range of factors, including:

  • The force of impact.
  • The characteristics of the surface that is impacted upon.
  • The characteristics of the structure through which the vibration transmits.
  • The characteristics of the radiating surface.

Impact sound can be prevented or reduced by:

Building Regulations Approved Document E - 'Resistance to the passage of sound' sets minimum standards for impact sound insulation.

Impact sound transmission is typically measured in-situ with a tapping machine which uses steel-faced hammers to strike a test surface and generate sound in an adjacent space which can be recorded or monitored. This is useful only in giving an indication of the likely level of impact sound as it does not accurately represent the variety of impacts that might be experienced in practice.

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