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Noise Exposure Calculator — HSE LEP,d, WHS & OSHA

Calculate daily noise exposure and dose for multiple tasks: Australia/NZ WHS (85 dB(A)), UK HSE LEP,d action values (80/85/87) and OSHA TWA (90 dB PEL).

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Disclaimer: This calculator provides a planning estimate. Actual workplace noise measurements must be conducted by a competent person using calibrated sound level meters per AS/NZS 1269.1 or equivalent standard. Peak levels are assessed separately and are not calculated here: LC,peak 140 dB(C) in Australia; 135 / 137 / 140 dB(C) peak action and limit values in the UK.
Noise tasks (up to 10)
Task 1

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Noise-Induced Hearing Loss and the Workplace

Noise-induced hearing loss (NIHL) is one of the most common occupational diseases worldwide. It affects workers in construction, mining, manufacturing, agriculture and entertainment. Unlike many injuries it is entirely preventable, but it is also irreversible: once the hair cells in the cochlea are damaged by excessive sound energy, they do not regenerate.

The measure used for compliance is daily noise exposure. It is written LAeq,8h in Australia, LEX,8h in ISO 9612 and the EU, LEP,d in the UK and TWA under OSHA, but in each case it is the total sound energy a worker receives over a working day, normalised to an 8-hour reference period. It follows the equal-energy principle: +3 dB is twice the acoustic energy, so it halves the allowed exposure time.

The LAeq,8h / LEP,d Formula

LAeq,8h = 10 · log₁₀ [ Σ (Tᵢ / 8) · 10^(Lᵢ / 10) ]

Where:
  Tᵢ = duration of task i in hours
  Lᵢ = A-weighted sound level during task i in dB(A)

Example:
  Task 1: 90 dB(A) for 2 hours
  Task 2: 80 dB(A) for 6 hours
  LAeq,8h = 10 · log₁₀ [(2/8)·10^(90/10) + (6/8)·10^(80/10)]
          = 10 · log₁₀ [0.25 × 10⁹ + 0.75 × 10⁸]
          = 10 · log₁₀ [3.25 × 10⁸]
          = 85.1 dB(A)

Two hours at 90 dB(A) is enough to take an otherwise quiet day (80 dB(A)) just over the 85 dB(A) line. The calculator's per-task chart shows which task contributes most to the dose, which is where controls should start.

Australia, the UK and the USA Compared

JurisdictionDaily exposurePeakExchange rate
Australia / NZ (model WHS Regulations, AS/NZS 1269.1)Exposure standard 85 dB(A) LAeq,8h140 dB(C)3 dB
UK (Control of Noise at Work Regulations 2005) and EULower action 80, upper action 85, limit 87 dB(A) (limit applies at the ear, with protection)135 / 137 / 140 dB(C)3 dB
USA (OSHA 29 CFR 1910.95)Action level 85 dBA, PEL 90 dBA (8-hour TWA)-5 dB

Australia and New Zealand

The model WHS Regulations define a single exposure standard for noise: an LAeq,8h of 85 dB(A) or an LC,peak of 140 dB(C), measured under AS/NZS 1269.1. A person conducting a business or undertaking must ensure no worker is exposed above either value, by working up the hierarchy of controls. Hearing protection is the last resort, and audiometric testing is required for workers who frequently rely on it. See the Safe Work Australia model Code of Practice on managing noise. The 80, 85 and 87 dB(A) values often quoted for Australia are actually the UK/EU scheme.

United Kingdom and EU

The UK Control of Noise at Work Regulations 2005 use a lower exposure action value of 80 dB(A), an upper exposure action value of 85 dB(A) and an exposure limit value of 87 dB(A), plus peak values of 135, 137 and 140 dB(C). The limit value takes the protection provided by hearing protectors into account. The HSE guidance on the noise regulations sets out the duties at each level. The daily personal noise exposure is called LEP,d in the UK and LEX,8h in the EU Directive.

United States

OSHA's occupational noise exposure standard (29 CFR 1910.95) uses a 5 dB exchange rate: every 5 dB increase halves the allowed time. The permissible exposure limit is 90 dBA over 8 hours. At an 8-hour TWA of 85 dBA (the action level) the employer must run a hearing conservation program and make hearing protectors available, and protectors must be worn at 90 dBA or more. This is less conservative than the 3 dB approach used elsewhere.

Selecting Hearing Protection

When exposure exceeds the criterion, the protector must bring the level at the ear below it. The calculator estimates the required SNR (Single Number Rating) as: Required SNR ≈ exposure − criterion + 4 (a 4 dB margin for real-world fit). For example, 98 dB(A) against an 85 dB(A) criterion needs SNR ≈ 98 − 85 + 4 = 17 dB. Avoid over-protection as well: a protector that cuts too much can impair communication and the detection of warning signals.

How to Use This Calculator

  • Select the standard: Australia / NZ, UK / EU or OSHA
  • Add a row for each task or activity during the workday
  • Enter the measured sound level in dB(A) and the duration of each task
  • Results update as you type: exposure level, dose percentage, compliance status and required SNR
  • The bar chart shows which tasks contribute most to the dose

Limitations

This is a planning estimate. It does not assess peak (C-weighted) levels, measurement uncertainty or impulsive noise, and it takes the sound levels you enter as given. Actual compliance assessments must use calibrated instruments and a competent person.

Frequently asked questions

What is the difference between LAeq,8h, LEX,8h and LEP,d?
They are the same quantity under different names: the A-weighted equivalent continuous sound level normalised to an 8-hour working day. Australia's WHS Regulations and AS/NZS 1269.1 call it LAeq,8h, ISO 9612 and the EU Noise Directive call it LEX,8h, and the UK Control of Noise at Work Regulations 2005 call it LEP,d. Because the scale is logarithmic, short loud periods dominate: 1 hour at 94 dB(A) plus 7 hours at 80 dB(A) gives 86.0 dB(A), well above the 80 dB(A) background.
What is the noise exposure standard in Australia?
The model WHS Regulations set the exposure standard for noise at an LAeq,8h of 85 dB(A) or an LC,peak of 140 dB(C). A PCBU must ensure a worker is not exposed above either value. There is no separate 80 dB(A) action level in the Australian regulations: the 80/85/87 dB(A) values belong to the UK and EU. Hearing protection is the last resort in the hierarchy of controls, and audiometric testing is required for workers who frequently need protectors to keep exposure down.
What are the UK noise action values and limit value?
Under the Control of Noise at Work Regulations 2005 the lower exposure action value is 80 dB(A) (LEP,d), the upper exposure action value is 85 dB(A) and the exposure limit value is 87 dB(A). The limit value takes any reduction from hearing protection into account, so it applies at the ear, not in the room. The peak sound pressure values are 135, 137 and 140 dB(C). At the lower value an employer must assess the risk and provide information and training; at the upper value hearing protection and hearing protection zones are required.
What are the OSHA noise limits in the USA?
OSHA 29 CFR 1910.95 sets a permissible exposure limit (PEL) of 90 dBA as an 8-hour time-weighted average, with a 5 dB exchange rate. At an 8-hour TWA of 85 dBA (the action level) the employer must run a hearing conservation program and make hearing protectors available at no cost. Protectors must be worn at a TWA of 90 dBA or more, or at 85 dBA or more for workers with a standard threshold shift or no baseline audiogram.
What is the difference between the 3 dB and 5 dB exchange rate?
The exchange rate sets how much the allowed time falls as the level rises. The 3 dB rate (Australia, UK, EU, ISO) follows the equal-energy principle: every +3 dB halves the allowed time, so 88 dB(A) is allowed for 4 hours against an 85 dB(A) criterion. OSHA's 5 dB rate is more lenient: every +5 dB halves the time, so 95 dBA is allowed for 4 hours against a 90 dBA criterion. The 3 dB rate is better supported as a predictor of hearing damage.
When must workers wear hearing protection?
It depends on the jurisdiction. In Australia the duty is to keep exposure at or below 85 dB(A) LAeq,8h and 140 dB(C) peak, using hearing protection only after higher-order controls. In the UK it is mandatory above the upper exposure action value of 85 dB(A). Under OSHA it must be worn at a TWA of 90 dBA or more (or 85 dBA with a threshold shift or no baseline audiogram). In every case the protector should bring the level at the ear below the relevant limit without over-protecting.
How do I reduce noise exposure at work?
Follow the hierarchy of controls: (1) eliminate the noise source; (2) substitute quieter equipment; (3) engineering controls such as enclosures, vibration isolation, acoustic barriers and maintenance; (4) administrative controls such as job rotation and scheduling noisy work when fewer people are present; (5) hearing protection as the last resort. Controls 1 to 4 are always preferred over personal protective equipment.
What does SNR or NRR mean?
SNR (Single Number Rating) is the European measure of hearing protector attenuation in dB and NRR (Noise Reduction Rating) is the US equivalent. Real-world attenuation is lower than the rated value, so this calculator adds a 4 dB margin: a protector needs SNR of at least the exposure level minus the criterion (85 or 90 dB(A)) plus 4. For example, 98 dB(A) against an 85 dB(A) criterion needs SNR of at least 17 dB.

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