FAQs

Noise from items of plant or machinery are best mitigated at source either by use of quieter machinery / processes or with barriers, screening and enclosures. Enclosures must be carefully designed so that they do not restrict the normal functioning of the plant / machinery. Measures such as sound insulation, silencers and enclosures may have the specific requirements that depend on the frequency characteristics of the source to be mitigated. Barriers and screening is most effective when very close to the source or very close to the receiver. As a general rule of thumb, you can achieve a 5dB(A) reduction by breaking the line of sight between a source and receiver.

Common mitigation measures include:

• Acoustic fencing or bunds
• Improved sound insulation / acoustic vents and glazing
• Acoustic enclosures / silencers
• Good acoustic design, such as relocation or reorientation of development / noise sources
• Management measures and best practice techniques, such as undertaking noisier operations at less sensitive times of the day, controlling material drop heights to minimise contact noise etc.

To control footstep noise (known as ‘impact sound’) you should first check that your floor construction provides sufficient airborne sound insulation and also check that the floor has a resilient layer. This resilient layer may be a rubber or foam layer within the floor and in some cases a carpeted floor with underlay will provide a suitable level of impact isolation. If not present you can add a suitable layer to the upper floor, but note that if you are considering a suitable floor design to provide both airborne and impact sound control in order to meet the Building Regulations Part E requirements (ADE 2003) you should contact an acoustic specialist to discuss your options.

Often small rooms have what is called ‘flutter’ echoes, whereby the sound bounces between two opposite hard parallel walls or parallel floor and ceiling. To break up such flutter echoes you can use soft material (padded furniture, curtains, canvas pictures over a hollow frame – also add absorbent felt/material to the back/cavity), bookshelves or other materials which have structure/shape to cause the sound to be broken up and dispersed. This can be added to one or both sides of the room.

A noise assessment can take anything from a matter of days for simple sites and applications to several weeks if detailed measurement, analysis and assessment is needed.

Noise surveys are typically weather dependent as British Standards require measurements to be taken in dry weather with low wind speeds. This means that the weather often dictates how quickly a noise survey and subsequent assessment and report can take place.

A desktop assessment (i.e. where no site visit is required) can be turned about quickly provided that all of the required information is provided.

Rest assured that you will be working with a professional consultancy that is focused on your requirements and can deliver a quality service in a timely manner. For a free quote and indication of our current timeframes for providing a noise assessment. Contact us here.

There is no fixed decibel level that can be described as ‘loud’ and perception of loudness can be relative both to the underlying sound environment and dependent on the frequency of the noise. Human hearing is most sensitive in the range of around 1kHz to 3kHz, which is within the frequency range of human speech.

All other things being equal, a change of 1dB is just perceptible under controlled / laboratory conditions, a change of 3dB is just perceptible under normal conditions and a change of 10dB is perceived as a doubling / halving of loudness.

The Control of Noise at Work Regulations 2005 sets limits on occupational noise limits with the aim of preventing damage to hearing.

• When levels exceed 85dB(A)* or 137dB(C)** hearing protection is mandatory, amongst other measures that must be taken by the employer and employee.
• When levels exceed 80dB(A)* or 135dB(C)** hearing protection must be provided by the employer but it is not mandatory for employees to wear it. There are also other measures that must be taken by the employer.
• Employees must not be exposed to noise levels above 87dB(A)* or 140dB(C)** taking account of any reduction in exposure provided by hearing protection.

* daily or weekly exposure **peak sound pressure level

The World Health Organisation provide recommended noise levels for environmental noise with the aim of protecting human health. The WHO recommends that noise levels should be reduced to below:

• Road traffic noise: 53 dB L_den and 45 dB L_night
• Railway noise: 54dB L_den and 44dB L_night
• Aircraft noise: 45dB L_den and 40 dB L_night
• Wind turbine noise: 45dB L_den
• Leisure noise: 70dB L_Aeq,24hr

There are other guidance documents that set levels of ‘acceptable’ noise within the planning process for specific noise sources, such as BS 8233 (transportation sources), BS 4142 (commercial / industrial sources), BB93 (noise impact on schools), PPG Minerals (quarries and similar processes such as aggregates recycling and disposal of construction waste), BS 5228 (for construction noise).

Broadly speaking there are three common scenarios:

• A planning condition may require you to provide the local authority with more information about noise in order to discharge that planning condition, for example providing details of the sound insulation to be installed at a site or providing a noise management scheme.
• A planning condition might have ongoing obligations, for example the requirement for regular noise monitoring and provision of the results to the local authority.
• A planning condition may simply set out the noise limit with which your operations need to comply. This may only require action if you receive complaints.

WBM will provide you with initial free advice on how to deal with planning conditions on noise. Contact us here.

BB93 covers both new build and conversion / refurbishment work in schools and sets standards for different teaching spaces including those used for students with special hearing or communication needs. Rooms that are to be used as SEND teaching spaces are required to have lower reverberation times and higher sound insulation between adjacent spaces. Reverberant sound and clarity of speech is exacerbated by large open spaces with hard reflective surfaces such as metal, glass and tiles. Adding in materials and structures to absorb and diffuse sound can help to make general use spaces more comfortable for those with hearing impairment or other special educational needs.

A permit may be required in addition to planning permission for a site. Whilst noise controls can be set in planning conditions, the Environment Agency will often require an additional assessment of noise following BS 4142. Permits will rarely set specific noise limits but there could be a requirement to “not cause pollution” or to “avoid unacceptable noise pollution”.

Approved Document E “Resistance to the Passage of Sound” 2003 deals with the Requirements of Part E of Schedule 1 to the current Building Regulations. Minimum performance standards are provided for sound insulation in residential from airborne (e.g. TVs & radios) and impact (e.g. footfall) sound. It also deals with reverberation in the common internal parts of buildings containing flats or rooms for residential purposes.

The core performance standards for dwelling houses or flats, depending on whether they are purpose built / formed by a material change of use, are 45 / 43 dB D_nTw+C_tr (minimum) for airborne sound insulation and 64 / 62 dB L’_nTw (maximum) for impact sound insulation.

Guidance on acceptable sound levels, including sound insulation and absorption, for educational buildings can be found in Building Bulletin 93 (BB93).

For healthcare buildings, compulsory acoustic performance requirements exist as set out in Health Technical Memorandum 08-01: Acoustics.

A noise survey should be undertaken by a suitably qualified acoustician (usually meaning someone with a recognised qualification in acoustics with relevant experience and a member of the Institute of Acoustics), who will be able to advise you of the details of the survey for your needs.

It will typically involve measurements using a calibrated Class 1 Sound Level meter. Depending on the circumstances, measurements will be undertaken of the noise source (if possible / relevant) and of the baseline sound levels (i.e. the existing sound environment, usually in the absence of the source under assessment).

Baseline sound levels can be undertaken as several sample measurements or using installed equipment over a period of at least 24 hours and to up to 1-2 weeks depending on the application. In some cases, if you are an operator, you may be required to cease your operations in order to measure the baseline sound environment in the absence of your operations.

BS 4142 “Methods for rating and assessing industrial and commercial sound” is a British Standard for assessing noise from industrial and/or commercial operations on residential properties. It includes the assessment of sound from industrial and manufacturing processes, M&E plant and equipment, loading and unloading of goods and materials, and mobile plant/vehicles on the site. It can be used to assess sound from proposed, new, modified or additional industrial/commercial sources, at existing or new premises used for residential purposes.

The basis of a BS 4142 assessment is to compare the specific noise level (i.e. the noise under investigation / assessment) to the background sound level in the absence of the specific noise. It is a tried and tested approach to assessing the significance of impact, which has seen little change to the method since its first publication back in 1967. In simple terms, the greater the difference between the specific noise and the background sound level, the greater the impact.

In contrast to other noise guidance, there is no fixed limit for acceptable noise. Acceptability is relative to the baseline sound environment, taking account of contextual factors such as:

• the time of day that the noise occurs
• the absolute level of the sound
• the character of the locality in which the noise occurs

As part of the assessment process, additional corrections (or decibel penalties) can be added to the specific noise to account for attention drawing characteristics that might render the noise more annoying than if devoid of such characteristics. The main features that attract corrections include intermittency (e.g. clear on / off conditions, regular / cyclic noise), tonality (e.g. a discrete hum or hiss), and impulsivity (e.g. a sudden onset noise).

This depends on the type of noise, locality and context.

For occupational noise at work, acceptable levels of noise are defined by exposure action values and limits in the Control of Noise at Work Regulations 2005.

For many situations, there may be noise controls or planning conditions attached to the site’s planning permission, licence or permit which set out what is considered to be the acceptable noise level.

For industry, and in the absence of any planning / permit controls, the noise level from the site may be compared to the background sound level in the absence of the site operating. The greater the difference between the two, the greater the level of impact and the more likely it is that the noise would be considered unacceptable.

For construction noise and minerals related activity there is guidance that sets upper threshold noise levels depending on the time of day, which can be used to define whether or not a noise may be acceptable.

There is no set decibel level that defines a nuisance level of noise.

Get in touch with WBM for free initial advice on your situation. Contact us here.

There is no set decibel level that defines a nuisance level of noise. The judgement of nuisance is decided by the Court or the local authority and will often depend on many factors such as the time of the day that the noise occurs, the context in which the noise occurs, the character of the noise and the frequency and duration of the noise. In most cases mere audibility of a noise is not sufficient for it to be unacceptable.

Get in touch with WBM for free initial advice on your situation. Contact us here.

See also “What is an acceptable noise level?”

Noise is commonly defined as ‘unwanted sound’. One persons sound is another’s noise and vice versa; perception of noise versus sound can therefore be highly subjective and is often influenced by preconceptions of the source of noise.

Noise (and sound) is measured in decibels (dB) with the A-weighting scale, dB(A), used to represent the sensitivity of human hearing. The frequency (or pitch) of noise / sound is measured in Hertz (Hz). The range of human hearing is from 20Hz to 20kHz, but we are most sensitive to noise in the range of around 1kHz to 3kHz, which corresponds to the frequency range of human speech.

Typically dense masonry materials work well at reducing sound transmission, such as brick and dense blockwork; however, lightweight materials such as timber and mineral wool absorption can be used to create high acoustic performing walls and floors. Options using both methods or a combination of both can help you achieve the requirements set out in the Building Regulations Part E requirements (ADE 2003).

A noise survey is most often required to establish whether you are causing or being affected by noise pollution.

A noise survey may be required as part of a planning application for new development and can be used to assess the existing sound environment, the impact of the existing sound environment on the new development or whether the new development will change the existing sound environment.

You might need a noise survey if your development is generating noise and you have noise conditions as part of your planning permission with which you have to comply (and provide evidence to demonstrate compliance) or if you have received complaints about noise.

For more information on whether you need a noise survey or for a free quote, contact us here.

A noise risk assessment is usually required in relation to the Control of Noise at Work Regulations 2005, which requires employers to take action to prevent or reduce risks to health and safety from noise at work. Additional advice can be found on the HSE website, who suggest as a guide that you may need to do something about noise in the workplace if:

• Employees have to raise their voice to carry out a normal conversation about 2m apart for most of the working day;
• Employees are exposed to noisy tools, machinery or areas for most of the working day;
• Employees are exposed to short periods of very loud or impulsive noise (e.g. hammering, explosive devices).

You can use noise dosemeters (dosimeters) to measure employees’ noise exposure over the working day but these can be subject to misuse and may be overly influenced by unusual or atypical activity close to the microphone; some employees may change their behaviour, which can skew the results.

For a tailored assessment to suit your specific work environment and needs, contact us here.

A noise survey / noise report may be required as part of the planning application process or once planning permission has been granted, e.g. to discharge a planning condition.

A noise survey and report are likely to be needed if:

• The proposed development is noise sensitive (e.g. schools, residential development)
• The proposed development will create noise which may affect nearby noise sensitive receivers (e.g. commercial activity, data centres, waste and recycling sites, general industry).

A noise survey report is most often submitted as part of the planning application process, with the main submissions in support of your development. A noise survey or report may be submitted during pre-application discussion, but it is more typical for these to advise you on the need for such works. As the noise report is usually submitted prior to the development taking place, the assessment will typically be based on calculations and the local authority may require a post-completion noise survey to be submitted (this may be a requirement of a planning condition) to demonstrate that the appropriate noise standards have been met. Where the application is retrospective, i.e. the development is already in place / operating, a noise survey report may be submitted with this application to demonstrate that acceptable noise levels are being achieved.