RBA Acoustics

Joint Guidance on the Impact of COVID-19 on the Practicality and Reliability of Baseline Sound Level Surveying and the Provision of Sound & Noise Impact Assessments

Joint Guidance on the Impact of COVID-19 on the Practicality and Reliability of

Baseline Sound Level Surveying and the Provision of Sound & Noise Impact

Assessments By the Association of Noise Consultants [ANC] and the Institute of Acoustics [IOA]

article found at: https://www.association-of-noise-consultants.co.uk/wp-content/uploads/2020/03/Joint-Statement-On-the-Impact-of-Covid.IOA-ANC.v1.230320.pdf?dm_i=142S,6SSFC,60HB0Z,R7UUM,1


The level of concern across the United Kingdom in relation to the spread of the COVID-19 means that there is now forced or self-imposed home working, along with restricted travel arrangements encouraged or enforced by the Government.

With regard to the provision of Sound and Noise Impact Assessments, many Members of the ANC and IOA, are finding their normal work practices impacted, such that even where opportunities to work from home exist, it will not be ‘business as usual’. Nevertheless, there will be a continuing requirement to maintain as far as possible the standard of our working practices, and also to maintain the flow of acoustic reporting which has an important role in the fabric and functioning of society. Acoustic reports are utilized for many purposes including to assist planning applications, the discharge of planning conditions and the implementation of Building Regulations. Continuing to provide high quality acoustic reporting in a timely manner for scrutiny by regulators and decision makers will allow the important aspects of planning to continue to move forward to support our society in the longer term beyond this national emergency.

As the responsible bodies, the ANC and IOA are keen to ensure that it is ‘business as usual’, as far as is practicably possible and responsible; not only to support continued on-going financial stability for our members, but also for the myriad strands of society that rely on our reports and input to projects. With the limitations on travel for all, we recognize that there will have to be changes to the manner in which acoustic monitoring and reporting is carried out (both how much and where). We have, therefore, recommended below some changes in working practices in the production of such reports. In so doing, it is still important to minimize uncertainties in surveying and to select appropriate baseline conditions, in a clear and transparent way. Furthermore, by good communication between those preparing the reports and those that will be reviewing them, the planning process (and other relevant processes) will be able to continue as smoothly as possible, without what could be a delay of many months.

We consider that by implementing these measures the provision of Sound and Noise Impact Assessments will be able to continue in a timely manner.


Appropriate sound level surveying should always be designed to obtain data which is representative of normal conditions, whilst taking account of variations in sound levels due to, for example, fluctuations in transportation traffic flows and industrial output. Acoustics professionals are skilled in understanding the effects of such variations and, therefore, check that results are representative and conclusions technically robust, so that clients and decisionmakers can come to well-informed judgements.

In these more uncertain times, where sound level climates may be affected by changing work patterns, school closures, etc. it is more important than ever that where surveys are undertaken, and the results assessed, these are done by suitably qualified professional acousticians.

Baseline Sound Level Measurements

The COVID-19 outbreak presents new challenges in obtaining representative baseline sound levels because typical road, air and rail transport usage have been reduced by travel restrictions and social distancing measures. Other sound sources may also be affected – for example, due to changes in operating patterns at industrial and commercial premises. However, other approaches can be taken to establish an appropriate robust estimate of baseline conditions, such as using existing data (for example, from previous local surveys and noise maps) or undertaking baseline sound predictions. These approaches can be supplemented by additional limited on-site sound level measurements, as necessary. Each of the possible options will need to be reviewed on a case-by-case basis, in order to identify the most appropriate approach, assessing the level of uncertainty and including this information in the reporting. Most importantly at this time, before progressing with surveying, there should be discussion of the intended approach with the relevant regulating authority.


For some projects there will be similar challenges when determining the sound levels associated with the development. Where possible, site visits to understand the sound environment will assist the professional in understanding the sources contributing to the sound environment, and where these may not be typical due to current circumstances. Any such site visits would need to comply with any restrictions on movement and ensure that social distancing is embedded within the site visit methodology.

For transport schemes, there may be a heavier reliance on predicted sound levels to describe the baseline conditions, with a corresponding need to source flow/activity data. There are now many sources of transport data available and these should be used, where possible, as an alternative to, or to augment direct site measurements to describe baseline conditions.

Where sound from existing facilities is needed to inform future noise levels, or where it is the existing sound that is being assessed, enquiries will be needed to understand whether or not the facility is running as normal. Discussions with other operators may be needed to understand whether nearby facilities are operating normally, and whether any changes might affect sound emissions. Examples may include where the BS4142 methodology is being used to assess the impact from an industrial / commercial facility following complaints, or where existing machinery needs to be measured to use as a reference for predicted future levels.

The acoustics professional will need to consider whether alternative sources of information in respect of sound levels can reasonably be used. Where appropriate, a case should be made regarding why any alternative methods are suitable for a robust assessment, and should clearly set out the estimated uncertainties in the assessment. In a small number of cases (most likely those relating to investigation of complaints), professional judgement will be needed as to whether the assessment can go ahead straightaway, or whether it would be prudent to wait until conditions are more representative of normal activities.

As with the determination of baseline conditions, discussions with the relevant regulators, who may be able to provide vital local knowledge, will be key.

Liaison with Regulators and Decision Makers

Liaison between acoustics professionals and relevant regulators is especially important during this period where environmental sound climates may vary from representative conditions. It is recognised that sites should be assessed on a case by case basis. A pragmatic approach may be needed with regard to the information required for planning applications and/or the discharge of planning conditions. Having said that, it will continue to be important that such assessments remain robust, and follow current good practice.

One outcome may be that supplementary information will be required at a later date or controlled by condition to allow planning authorities to maintain momentum in the planning system during this period.


In summary, we are experiencing extremely unusual conditions but yet, it is essential that we continue to exercise our professional skills diligently and cope with these changed circumstances. The advice contained in this guidance is not new, and all professionals have probably had to cope previously with unusual circumstances from time to time in their day to day life. It is just that, at the moment, every day presents an unusual situation.

It is important that decision making and associated development continue, including the planning process and the discharge of planning conditions. But it is also important to avoid poor decisions being made because the highest standard of acoustic assessment was not maintained during these challenging times.

Version 1
The Association of Noise Consultants
The Institute of Acoustics
23rd March 2020.

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