dBx Acoustics

Jargon Buster – BS 4142 Noise Assessment

The latest in our “jargon buster” series looks at what a BS 4142 noise assessment is – what it’s intended to cover, how it works, and when you might need to commission one from an acoustic consultant.

BS4142:2014 Methods for rating industrial and commercial sound essentially does what it says on the tin. It’s used for a variety of situations, for example:

  • Assessing noise from a new fan or piece of equipment to be installed
  • Assessing the potential impact of a new commercial or industrial enterprise on surroundings
  • Assessing the likelihood of complaint from residents arising from a new industrial or commercial development
  • Quantifying whether existing complaints based on subjectivity have an objective basis for action

It is important to understand that the standard does not allow a nuisance to be determined. It is also not appropriate for use in certain circumstances, for example, to quantify the impact of noise from events and entertainment.

BS 4142 noise survey

The first step in carrying out a BS 4142 assessment is to gather information. This will usually involve a noise survey, which has two aims – firstly, to ascertain the prevailing background noise level (LA90) at the noise sensitive receptors, and secondly, if the noise source to be assessed already exists, to quantify that noise source.

For a prospective development or installation, it is possible to predict future noise levels based on manufacturers’ information. Alternatively, you can take measurements of similar activities. We recently worked for a factory in Huddersfield which was seeking planning permission for an extension. We were able to measure noise levels from their existing equipment, calculate the level of sound breaking out through the proposed structure of the extension, and predict how much noise would arrive at the nearby housing.

The level of noise arising due to the proposed industrial / commercial activity is the ‘specific noise level’, LAeq. This can be adjusted for the ‘on time’ of specific activities during the day and night time period.

Developing the rating level

The ‘rating level’ is developed from the specific noise level, but if appropriate includes corrections for specific noise characteristics. For example, if the proposed noise source will be intermittent, tonal (whiny), contain bangs or clanks, or any other characteristic which would make it particularly noticeable, a correction is added to the specific noise level. The latest iteration of BS 4142 allows for a variety of corrections to be added at the discretion of the surveyor/assessor – this is in contrast to the flat +5dB correction provided for in the previous iteration of the standard.

Assessing the likelihood of noise complaints

Assessments are based on 1 hour during the day, and a 15 minute period at night (11pm-7am). The rating level is compared to the background noise level, and the difference is used to give an idea of the likelihood of complaint: the greater the difference, the greater the likelihood of complaint.

A difference of around +10dB or more is likely to be an indication of a significant adverse impact, depending on the context.

A difference of around +5 dB is likely to be an indication of an adverse impact, depending on the context.

The lower the rating level is relative to the measured background sound level, the less likely it is that the specific sound source will have an adverse impact or a significant adverse impact. Where the rating level does not exceed the background sound level, this is an indication of the specific sound source having a low impact, depending on the context.

You can see that this remains quite a woolly and subjective assessment – although the wording has been changed in this iteration of the standard, there is still a lot of flexibility according to ‘context’, and little guidance. This is where using a professional consultant can be vital; they will negotiate with the planning officer on your behalf to agree an appropriate level for noise emissions. 

Do I need a BS 4142 assessment?

It’s likely that if you are seeking planning permission for an industrial use, or for new externally mounted plant, a planning condition will be set requiring that an assessment is carried out and submitted before work commences.

You may also want to consider an assessment if you are considering equipment or activity for which you don’t need planning permission, but which may have an effect on your neighbours. It can be wise to protect yourself by establishing baseline noise levels before you go ahead, so that there is a reasonable rebuttal should any complaints be received in future.

How do I commission an assessment?

Make sure you are talking to a competent consultant who is a full member of the Institute of Acoustics (MIOA). They will be able to talk through your specific project and provide you with a clear scope of work and fee to get the job done.

dBx Acoustics has extensive experience of BS 4142 noise assessments, and of helping to design noise control solutions to ensure that planning is achieved. If you would like to know more about how we can help you, please contact us.

dBx Acoustics

Noise, Fatigue and Acoustic Design In Call Centres

We are all familiar with call centres – and most of the time when we talk about them it’s from the caller’s point of view. Are you frustrated when you are put through to someone in another country? Does the fake friendliness of the scripted interaction annoy you? But step back for a moment and remember some of those calls – was there something else that bothered you?

I know from my own experience that many a time I have been able to hear the operator on the next phone, and sometimes the whole hubbub of the call centre, which both makes it difficult to focus on your own conversation, and may give you some concerns about the privacy of your own conversation.

Noise transfer between call stations, and the build up of noise in general, is even more of a problem for call handlers, who need to maintain their focus over many hours. High background noise levels lead to physical and mental fatigue and therefore reduced efficiency, as well as the potential for operators to suffer from vocal fatigue which may lead to higher than normal absence rates through sickness. A 2008 study found that 28.7% of workers suffered permanent auditory fatigue, and that by the end of the working day this number had risen to 71.3%. The same study showed 48% of workers reporting vocal problems over the previous 12 month period.

This issue isn’t about to go away, either – the world’s largest call centre, with 20,000 seats, is about to open in China.

In the UK, over a million people work in the industry and there are over 5,000 call centres. Clearly both from the point of view of employer’s extracting the best and most efficient work from their employees, and for the health and welfare of the employees themselves, acoustic conditions in call centres need to be carefully considered, whatever their size.

Whether you’re planning a new contact centre, or having issues in an existing facility, it’s worth talking to a qualified acoustic consultant before you embark on the installation of acoustic treatments. A careful balance of both screening and acoustically absorptive finishes is required, and even the noise produced by the ventilation system can be used to help provide some sound masking. A consultant such as dBx Acoustics can model the space and demonstrate the auditory effect of different treatment options, allowing the client to assess the relative benefits and costs of various treatment schemes. Being able to optimize the placement and quantity of acoustic treatments allows a more effective and cost-conscious approach to acoustics, rather than just installing some absorptive treatments and hoping for the best.

Happier, healthier call centre workers? More calls, dealt with better, with lower staff absence rates? It sounds good to us. If you would like to talk to dBx Acoustics about how we can help you with call centre acoustics, please contact us!

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