How do I comply with the Noise at Work Regulations? To comply with the Noise at Work Regulations, employers must assess noise exposure, reduce noise at source where reasonably practicable, manage remaining risk with organisational controls and hearing protection, train workers, keep records, and review assessments when conditions change.
Workplace Noise Surveys Explained: dB(A), dB(C) and UK Action Levels
Introduction: Why noise survey results often confuse employers
Many employers do the right thing and commission a workplace noise survey — only to receive a report full of numbers, acronyms, and unfamiliar terminology:
• dB(A)
• dB(C)
• LEAV / UEAV
• Peak sound pressure
• Daily exposure values
Without clear explanation, it’s hard to know:
• whether the results are a problem,
• what action is legally required,
• or how urgently changes need to be made.
This blog explains exactly what noise survey results mean, in plain English, so you can interpret them confidently and take the right next steps.
How this blog fits into the 3-part series
This article is Part 2 of the Noise at Work blog series:
• Part 1: Do I need a noise at work risk assessment or a noise survey?
• Part 2 (this blog): Understanding workplace noise survey results
• Part 3: How to comply with the Control of Noise at Work Regulations using HSE L108
If you’re unsure whether you needed a survey in the first place, start with Part 1. If you already have survey results and want to know what to do with them, Part 3 is next.
What is a workplace noise survey?
A workplace noise survey (also known as a noise exposure assessment or occupational noise survey) is a structured process used to measure how much noise workers are exposed to during their normal work activities.
The purpose of a noise survey is to:
• quantify noise exposure accurately,
• compare exposure against legal thresholds,
• identify who is most at risk,
• and inform practical control measures.
Unlike a one-off sound reading, a proper survey considers how noise varies over time, between tasks, and between different roles.
The two types of noise measured in a survey
A workplace noise survey always considers two different types of noise risk, because they affect hearing in different ways:
1. Average noise exposure over time (dB(A))
2. Peak or impact noise (dB(C))
Understanding the difference between these is essential.
What does dB(A) mean? (Explained simply)
dB(A) is a unit used to measure average noise exposure over time, adjusted to reflect how the human ear responds to sound. It is used to assess the risk of long-term hearing damage.
Why dB(A) matters
The human ear is more sensitive to some frequencies than others. The “A-weighting” filters sound measurements so they broadly match human hearing sensitivity.
dB(A) is used to calculate:
• daily noise exposure (over a shift), or
• weekly noise exposure (where work patterns vary).
This allows short loud tasks and longer quieter tasks to be combined into a single exposure value.
Understanding daily and weekly noise exposure
Noise exposure is not just about how loud something is — it’s also about how long workers are exposed. For example:
• A machine running at 90 dB(A) for 10 minutes is less risky than the same machine running for 6 hours.
• Several short, noisy tasks spread through the day can combine to create high daily exposure.
Noise surveys calculate exposure based on real working patterns, not worst-case assumptions.
What does dB(C) mean? (Peak and impact noise)
dB(C) is used to measure peak or impact noise, such as sudden loud bangs or explosive sounds that can cause immediate hearing damage.
Examples of peak noise
Peak noise often comes from:
• hammering or riveting,
• press tools,
• drop forging,
• cartridge-operated tools,
• sudden release of compressed air,
• dropping heavy metal items.
Even if these noises are brief, they can still cause injury, which is why they have separate limits from average exposure.
UK noise action values explained clearly
UK law sets three tiers of noise thresholds, each with increasing legal duties.
Lower Exposure Action Values (LEAV)
• 80 dB(A) daily or weekly exposure
• 135 dB(C) peak noise
What this means in practice: At or above this level, employers must:
• assess the risk,
• provide information and training,
• consider noise reduction.
Upper Exposure Action Values (UEAV)
• 85 dB(A) daily or weekly exposure
• 137 dB(C) peak noise
What this means in practice:
At or above this level, employers must:
• implement stronger noise control measures,
• provide hearing protection where risk remains,
• introduce hearing protection zones where appropriate.
Exposure Limit Values (must not be exceeded)
• 87 dB(A) (after hearing protection is taken into account)
• 140 dB(C) peak noise
What this means in practice: These are absolute limits. Exposure must be reduced below these values.
Why duration is just as important as loudness
Noise risk depends on how loud the noise is and how long exposure lasts. Short loud tasks repeated through the day can produce the same exposure as continuous noise.
This is why:
• task-based measurements,
• and personal noise dosimetry,
are often used in complex workplaces.
How workplace noise surveys are carried out
A competent noise survey usually includes:
1. Initial walkthrough Understanding processes, tasks, and working patterns.
2. Task identification Identifying which activities contribute most to exposure.
3. Noise measurements Using calibrated sound level meters and/or personal dosimeters.
4. Exposure calculations Combining measurements with duration to calculate daily/weekly exposure.
5. Peak noise assessment Identifying any impact noise risks.
6. Clear reporting Translating results into compliance decisions and actions.
What a good noise survey report should tell you
A high-quality noise survey report should make it easy to answer:
• Who exceeds 80 dB(A)?
• Who exceeds 85 dB(A)?
• Are there any peak noise issues?
• Which tasks create the most exposure?
• What controls will reduce exposure most effectively?
• Do we need hearing protection zones, and where?
If your report only lists numbers without clear conclusions, it is not doing its job.
Common mistakes when interpreting noise survey results
Employers often misunderstand results by:
• focusing only on the highest reading rather than exposure,
• assuming PPE solves the problem automatically,
• ignoring peak noise because it is “brief”,
• failing to review results after changes,
• or not acting because results are “just over” action values.
HSE expects proportionate but decisive action when thresholds are exceeded.
Key Takeaways
• dB(A) measures average noise exposure over time.
• dB(C) measures peak or impact noise.
• 80 dB(A) and 85 dB(A) trigger increasing legal duties.
• Duration of exposure is as important as loudness.
• Noise survey results must lead to clear action.
How NOVA Acoustics makes noise survey results usable
NOVA Acoustics focuses on turning technical data into practical compliance decisions.
Our noise surveys provide:
• Plain-English summaries
• Clear statements on action values
• Practical noise control options
• Advice on hearing protection zones
• Support with follow-up assessments
Noise at Work Surveys & Assessments: https://www.novaacoustics.co.uk/noise-at-work-surveys-and-assessments/
Example complex survey project (PepsiCo International): https://www.novaacoustics.co.uk/projects/occupational-noise-survey-pepsico-international/
Workplace Noise Surveys Across the UK
NOVA Acoustics delivers workplace noise surveys nationwide, including:
• Manchester – https://www.novaacoustics.co.uk/manchester/
• Leeds – https://www.novaacoustics.co.uk/leeds/
• Newcastle – https://www.novaacoustics.co.uk/newcastle/
• Nottingham – https://www.novaacoustics.co.uk/nottingham/
• Sheffield – https://www.novaacoustics.co.uk/sheffield/
• Cambridge – https://www.novaacoustics.co.uk/cambridge/
• London & Home Counties – https://www.novaacoustics.co.uk/london/
• Hull & East Yorkshire – https://www.novaacoustics.co.uk/hull/
• Birmingham – https://www.novaacoustics.co.uk/birmingham/
• Bristol – https://www.novaacoustics.co.uk/bristol/
• Liverpool – https://www.novaacoustics.co.uk/liverpool/
Workplace Noise Surveys Across the UK
How much does a workplace noise survey cost?
Costs depend on site size, number of tasks, and monitoring needs. NOVA Acoustics provides proportionate quotes aligned with actual risk.
How long does a noise survey take?
Most surveys take half a day to one day onsite, depending on complexity.
Are phone noise apps acceptable for compliance?
No. They are not sufficiently accurate or reliable for legal compliance.
Can exposure be averaged over a week?
Yes, where work patterns vary significantly between days.
Do office environments need noise surveys?
Usually no, unless there is a specific noise risk.
What happens after the survey?
You receive a clear report explaining results, risks, and next steps.
Recent posts
What does a workplace noise survey measure? A workplace noise survey measures average noise exposure over time (dB(A)) and peak or impact noise (dB(C)) to determine whether workers exceed UK legal action values under the Control of Noise at Work Regulations.
Do I need a noise at work risk assessment or a noise survey? If workers may be exposed to harmful noise (around 80 dB(A) or above), UK law requires a noise at work risk assessment. If exposure cannot be confidently estimated, a noise survey with measurements is required to demonstrate compliance.