Airborne sound
Sound is caused by vibrations which transmit through a medium and reach the ear or some other form of detecting device. Sound is measured in loudness (decibels (dB)) and frequency (Hertz (Hz)).
Airborne sound (or airborne noise) is sound that is transmitted through the air.
Typically, airborne sound might be generated by:
This is as opposed to structure-borne sound that results from an impact on or a continuous vibration against a part of a building fabric resulting in sound being radiated from an adjacent vibrating surface. An example of structure-borne sound is footsteps of a floor being heard in a room below.
Whilst they are sometimes considered to be separate phenomena, airborne and structure-borne sound are related, in that airborne sound can cause structure-borne sound and vice versa. Airborne sound may cause an element of the building fabric to vibrate when it encounters a surface, and structural vibrations may radiate from a surface, generating airborne sound.
Poor detailing or poor standards of workmanship can result in airborne sound transmitting directly between spaces, for example through gaps around the edge of doors, and may result in flanking sound, where sound travels around a separating element, even though the element itself might provide exceptionally good acoustic insulation. Even exceedingly small gaps can cause a significant increase in the transmission of airborne sound.
Problems can also occur where doors, windows, or other openings face onto ‘noisy’ spaces, such as a circulation space, a busy road, or a school playground. If this deters occupants from leaving elements of the building open, this can affect the performance of natural ventilation strategies.
The amount of airborne sound in a space can be reduced by acoustic absorption, which reduces the amount of sound reflecting back into the space from the surfaces enclosing it, by acoustic insulation which reduces the amount or sound transmitting into the space from an adjacent space through the building fabric and by the elimination of gaps that might permit direct transmission.
Airborne sound transmission can be tested by placing a loudspeaker in a space to generate sound at a range of frequencies, and detecting any resulting sound in an adjacent space with a microphone. The difference is then calculated and adjustment made to take into account the sound absorption characteristics of the ‘receiving’ space. Tests are typically carried out in the range from 125 Hz to 4000 Hz.
Building Regulations Approved Document E - 'Resistance to the passage of sound' sets minimum standards for airborne sound insulation.
[edit] Related articles on Designing Buildings Wiki
- Acoustics in the workplace.
- Approved Document E.
- Audio frequency.
- Building acoustics.
- Building Bulletin 93: acoustic design of schools.
- Decibel.
- Impact sound.
- Flanking sound.
- Noise nuisance.
- Part E compliance.
- Pre-completion sound testing.
- Reverberation time.
- Robust details certification scheme.
- Room acoustics.
- Sound absorption.
- Sound frequency.
- Sound insulation.
- Sound power.
- Sound reduction index (SRI).
- Sound v noise.
- Structure-borne sound.
- Suitable insulation can help preserve the golden sound of silence.
Featured articles and news
HBPT and BEAMS Jubilees. Book review.
Does the first Labour budget deliver for the built environment?
What does the UK Budget mean for electrical contractors?
Mixed response as business pays, are there silver linings?
A brownfield housing boost for Liverpool
A 56 million investment from Homes England now approved.
Fostering a future-ready workforce through collaboration
Collaborative Futures: Competence, Capability and Capacity, published and available for download.
Considerate Constructors Scheme acquires Building A Safer Future
Acquisition defines a new era for safety in construction.
AT Awards evening 2024; the winners and finalists
Recognising professionals with outstanding achievements.
Reactions to the Autumn Budget announcement
And key elements of the quoted budget to rebuild Britain.
Chancellor of the Exchequer delivers Budget
Repairing, fixing, rebuilding, protecting and strengthening.
Expectation management in building design
Interest, management, occupant satisfaction and the performance gap.
Connecting conservation research and practice with IHBC
State of the art heritage research & practice and guidance.
Innovative Silica Safety Toolkit
Receives funding boost in memory of construction visionary.
Gentle density and the current context of planning changes
How should designers deliver it now as it appears in NPPF.
Sustainable Futures. Redefining Retrofit for Net Zero Living
More speakers confirmed for BSRIA Briefing 2024.
Making the most of urban land: Brownfield Passports
Policy paper in brief with industry responses welcomed.
The boundaries and networks of the Magonsæte.