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] Version 2, 24th March 2020



The level of concern across the United Kingdom in relation to the spread of the COVID-19 means that there is now forced home working, along with restricted travel arrangements being 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 very tight limitations on travel for all, we recognize that there will have to be changes to the manner in which acoustic assessment and reporting is carried out. 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 when determining 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.



Site surveys should only take place if they can be carried out in complete accordance with current Government requirements. Instead, as set out below, alternative methods of characterising baseline conditions may be used. Acoustics professionals are skilled in understanding how best to use those techniques so that the outcome is representative and the conclusions drawn are technically robust, so that clients and decision-makers can come to well-informed judgements.

Baseline Sound Level Characterisation

Before the most recent restrictions, the COVID-19 outbreak presented 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 have been affected – for example, due to changes in operating patterns at industrial and commercial premises. However, now that site visits cannot routinely occur, other approaches may have to 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, where permitted. The most appropriate option to use must be determined on a case-by-case basis, assessing the level of uncertainty and including this information in the reporting. Most importantly at this time, before progressing with any methodology, 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 permitted, 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 will have to be a 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, along with previously made 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 the proposed alternative methods are suitable for a robust assessment, and should clearly set out the estimated uncertainties in the assessment. In cases relating to the investigation of complaints it may not be possible to carry out any form of site measurement at the moment, regardless of whether the conditions are representative of normal activities.

Therefore, this type of assessment is likely to have to be postponed. 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 characterising environmental sound climates cannot be undertaken in the conventional way. It is recognised that projects 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.


The Association of Noise Consultants
The Institute of Acoustics