Noise impact assessment

Noise Impact Assessment

Planning conditions for all new developments, especially residential, schools and healthcare, require a noise impact assessment. A Noise impact assessment involves comparing the predicted noise levels from the proposed development against the prevailing background noise levels.

Noise Surveys

By measuring existing noise levels in an area, we can establish an appropriate noise level for new noise sources to avoid disturbance and ‘noise creep’. We also calibrate noise maps (see below) to show how sound propagates across a built up area.

Noise surveys are used to assess the impact of environmental noise on a new development, particularly residential developments, where they allow us to establish the acoustic strategy for ventilations and facades (BS 8233 assessment).

Where new noise sources will be introduced, noise surveys are the basis for a BS 4142 assessment (see below) to establish the level of disturbance occasioned to surrounding premises.

BS 4142 Assessment

BS 4142 is the standard used to assess the potential for disturbance arising from industrial and commercial noise sources. In a BS 4142 assessment, the noise from an existing or future noise source is compared against the existing background sound level. Penalties are applied for acoustically distinctive characteristics such as intermittency or tonality. Based on the difference between the ‘rating level’ and background and considering the acoustic context of the area, the likelihood of disturbance to surrounding areas can be predicted.

A BS 4142 assessment is usually required at the planning stage for new industrial and commercial noise sources. It can also be carried out where noise complaints are received to investigate whether there is a basis for the complaints.

Noise Mapping and Modelling

For complex sites, noise modelling is a great way to investigate how new noise sources will affect the surrounding area. Models allow us to consider factors such as the landscape, screening from buildings and the location of new noise sources.

We calibrate models using the data gathered from noise surveys, which means multiple noise sources in an area (e.g. roads, industry, rail) can be accurately represented. Models also allow us to optimise mitigation measures such as bunding and noise barriers, saving money for the client while making sure the surrounding area is appropriately protected from noise.

Here’s our recent work


dBx Case Studies - Education

There is a proven link between acoustic conditions in schools and educational outcomes. Building Bulletin 93 (BB93) mandates minimum standards in primary and secondary schools for noise levels and room acoustics, as well as acoustic separation between teaching spaces.

The dBx Acoustics team can help you comply with BB93, but our expertise goes even further. We have extensive experience designing environments for pupils with additional needs, including autism and hearing loss, as well as higher education and noisier, practical workshop spaces.

New and refurbished school buildings must comply with Building Regulation E4 and the acoustic performance standards of Building Bulletin 93 (BB93) ‘Acoustic Design of Schools’. Whilst BB93 is not mandatory for higher education establishments, it typically forms the basis of the initial design for such establishments, with modifications as appropriate to allow for specific HE uses. Where projects are being designed with BREEAM in mind, credits HEA05 and POL05 are also relevant.

There are a number of different acoustic aspects which come together to ensure that acoustic conditions in schools are appropriate to support learning, and it’s so important to get it right – studies have shown that educational attainment can be directly correlated to acoustic conditions.

Our involvement often begins at the planning stage with an environmental noise survey, which allows us to advise on ventilation and glazing requirements to control noise ingress to the building. If mechanical ventilation is proposed, if there is an external MUGA, or if community use is proposed, the noise survey also allows noise emission limits to be set to ensure that existing neighbours are not adversely affected by noise.

Internal ambient noise levels in teaching spaces are also affected by mechanical ventilation, and we work with the M&E consultant to specify appropriate noise control measures, such as silencers.
When it comes to the design of the building itself, BB93 requires us to specify partitions and floors to control airborne and impact sound transmission between teaching spaces, based on their relative sensitivity and noise generation characteristics. The detailing of junctions and sealing of any services penetrations is critical in maintaining acoustic separation between adjacent rooms.

Having provided a suitably quiet teaching environment which won’t be adversely affected by activity in other classrooms, our focus moves to room acoustics and control of reverberation. Often this is as simple as specifying the acoustic performance of a suspended ceiling, but for large spaces such as Assembly Halls and Sports Halls, we undertake acoustic modelling to optimise the specification and placement of acoustic finishes. Where an exposed soffit is preferred, we calculate the specification and quantity of finishes, such as acoustic rafts and wall panels to control room acoustic conditions.

Finally, we carry out pre-completion acoustic testing on-site to ensure that all of the acoustic criteria for the project have been complied with on-site.

The dBx Acoustics team also have a particular interest in acoustic design for SEN schools, particularly schools catering to neurodiverse pupils. BB93 specifies design criteria for “children with special hearing and communication needs”, which is intended to include autism, ADHD and auditory processing difficulties, and assists in providing an environment in which speech transmission is clear and effective. The standard does not, however, consider the other acoustic aspects of school life which affect such pupils, including auditory sensitivities and the need to provide spaces to allow a retreat from the noise and bustle of daily school life. Our team’s direct and personal experiences of neurodiversity, both as parents and as individuals, helps us to understand the requirements of individual educational clients, and help guide the design of educational buildings to provide an acoustically diverse and appropriate environment.

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