Noise Exposure Calculator: Daily LAeq,8h and Noise Dose

The 8-hour equivalent noise level and the daily noise dose from the levels a person is exposed to and for how long.

Calculated from standard textbook formulas, with every step shown. The formulas are fixed, so the working does not need checking: what matters is the numbers you type in. Use these calculators only if you are competent to choose the inputs (loads, material strength, dimensions, supports) and check your units and assumptions. For learning and checking your own working: design and sign-off are for a qualified engineer. Drafting Central does not store the numbers you type.

How this calculator works

Noise exposure at work depends on both how loud it is and how long a person is exposed. Because sound is measured on a logarithmic scale, the loudest part of the day usually dominates: a short time at a high level can matter more than a long time at a moderate one.

The calculator turns each level into noise energy, multiplies by the time, adds the energy up and spreads it over an 8-hour day to give the equivalent level LAeq,8h. The daily dose compares the energy with the energy at the exposure standard, so 100 percent means exactly at the standard.

The exposure standard is an input because it comes from the work health and safety regulation, which can change. Hearing protection is the last control: the law and the noise code of practice are to remove the noise or reduce it at the source first. Noise must be measured by a competent person with proper equipment.

Formulas used

  • L_{Aeq,8h} = 10 \log_{10}\left(\frac{\sum t_i 10^{L_i/10}}{8}\right)
  • D = 100 \times \frac{\sum t_i 10^{L_i/10}}{8 \times 10^{L_{std}/10}}

Worked example

With the default numbers in the calculator above:

  1. Level 1: noise energy in the time: 4.000e+9 (relative)
  2. Level 2: noise energy in the time: 400000000 (relative)
  3. Equivalent 8-hour level: 87.4 dB(A)
  4. Daily noise dose against the standard: 173.9 %
  5. Margin to the standard: -2.404 dB

Change the numbers in the calculator to see the full working, every step, for your own case.

Common questions

What does a dose of 100 percent mean?

The exposure is exactly equal to the exposure standard for an 8-hour day. Above 100 percent is over the standard.

Why is peak noise separate?

A single very loud bang or impact can damage hearing even when the 8-hour average is low, so the peak level is assessed against its own standard.

Does a result below the standard mean there is no problem?

It means the exposure is below the standard on the numbers you entered. The numbers must come from proper measurement, and the duty to reduce noise so far as is reasonably practicable remains.

Related calculators

Further reading: Managing noise and preventing hearing loss at work Code of Practice (Queensland); Safe Work Australia noise guidance; AS/NZS 1269 (occupational noise management, licensed).

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