Noise Impact Assessments: What are they and why do we need them?

Matt Elliott: 23 November 2021

What is a Noise Impact Assessment?

Noise Impact Assessments (NIAs) consist of a series of detailed noise surveys, which are often required for a variety of planning applications. These are requested by Local Planning Authorities (LPA), in particular by Environmental Health Officers (EHOs), in order to establish the environmental noise impacts of existing and proposed developments. An NIA will typically involve an assessment of the existing noise climate and comparison of the predicted noise level generated by the proposed development. NIAs are generally requested by an LPA due to concerns arising from noise exposure to prospective or existing noise sensitive properties.  

Typical focus of NIAs:

  • Transport noise (Road, Rail, and Aircraft) to proposed noise sensitive developments (BS8233:2014);
  • Noise from new fixed plant at existing residential receptors (BS4142:2014);
  • Noise from existing commercial units upon proposed noise sensitive developments (BS4142:2014);
  • Noise due to road traffic generated by the development (Change in Ambient).

NIAs work in conjunction with the relevant British Standard which lay out the acceptable level of noise permitted in various settings, and subsequently any mitigation that may be required to attain these levels. Through the use of acoustic barriers, bunds, alternative ventilation, and good acoustic design, the effects of noise can be heavily mitigated against, and thus ensuring the wellbeing of existing and future occupants of newly-built or existing residential dwellings.  

Noise modelling is imperative in the work that we do. Noise models are created, through using state of the art CadnaA software, which can accurately predict noise levels, and how they propagate over a site. Figure 1 demonstrates how, through the use of colours and bands, we can effectively demonstrate to clients the feasibility of a site, which is an integral part of a Noise Constraints Assessment. Noise Constraint Assessments are often used at the infant stage of a large development, whereby the assessment can inform developers of potential constraints and take these into consideration through the design phase. A variety of noise sources can be inputted into the noise map, from transport (Figure 1) to single source output (Figure 2) which can significantly effect the propagation of the noise. Cadna also has a 3D function (Figure 3), which can be particularly useful in high rise blocks or buildings with large facades, where noise levels can vary significantly.

Why do NIAs matter?

Noise can have an effect on health, wellbeing, productivity and the natural environment. Noise is considered to be any unwanted or disturbing sound that affects the health and well-being of humans and other organisms. Noise pollution impacts millions of people on a daily basis. Exposure to loud noise can also cause high blood pressure, heart disease, sleep disturbances, and stress. These health problems can affect all age groups, especially children. Many children who live near noisy airports or streets have been found to suffer from stress and other related issues, such as impairments in memory, attention level, and reading skills.

Cities have become the epicentre of this type of pollution, which, is severely damaging to humans . So much so that the European Environment Agency estimates that noise is responsible for 72,000 hospital admissions and 16,600 premature deaths every year in Europe alone. (Noise — European Environment Agency ( In the UK alone, cities take up 8% of the land whilst accounting for 54% of the population. As cities expand larger and urban populations grow, the problem of noise pollution will only get worse, and thus the focus upon mitigating all forms of noise pollution will become ever more prevalent and important.


Omnia has extensive experience of producing NIAs for a number of clients, with varying sized developments. We’d be happy to assist you in any upcoming projects or enquiries you may have, and look forward to working with you.

If you’d like Omnia’s help with your project, contact us to speak to one of our team.