Noise Dose Percentage Calculator

Work out noise dose percentage instantly with clear inputs, formula shown and shareable results.

About Noise Dose Percentage Calculator

Permitted exposure time halves for every exchange rate increase in level: at a five decibel exchange rate, 90 dBA is allowed for eight hours and 95 dBA for four. Dose is actual time divided by permitted time, and the equivalent eight hour average follows from inverting the same relation. Fifty percent dose, equivalent to 85 dBA, is the usual action level.

Formulas

Permitted time

T = 8 / 2^((L - criterion) / exchange rate)

Dose and TWA

Dose % = 100 x C / T; TWA = criterion + exchange rate x log2(dose / 100)

Worked example

With the default values below, Noise Dose Percentage Calculator returns Noise dose of 98.96%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Measured sound levelaccepts 40–140 dBA: 92 dBA
Exposure durationaccepts 0.05–24 h: 6 h
Criterion levelaccepts 70–100 dBA: 90 dBA
Exchange rateaccepts 3–6 dB: 5 dB

Results

Noise dose: 98.96% %
Permitted exposure time: 6.063 h
Eight hour time weighted average: 89.92 dBA
Assessment: Above the action level — enrol in a hearing conservation programme

Step by step

1Values used
2Permitted time
3Dose and TWA
4Noise dose= 98.96 %
5Permitted exposure time= 6.063 h
6Eight hour time weighted average= 89.92 dBA
7Assessment= Above the action level — enrol in a hearing conservation programme

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Preliminary estimate only. Noise exposure assessment must follow the measurement standard and criterion adopted by your regulator and be carried out by a competent person.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Noise exposure assessment must follow the measurement standard and criterion adopted by your regulator and be carried out by a competent person.

Frequently Asked Questions

How is the Noise Dose Percentage figure worked out?

T = 8 / 2^((L - criterion) / exchange rate). Permitted exposure time halves for every exchange rate increase in level: at a five decibel exchange rate, 90 dBA is allowed for eight hours and 95 dBA for four.

Why do three and five decibel exchange rates both exist?

Three decibels is the equal-energy rule and is used in Europe and by most researchers. Five decibels is a historical US regulatory compromise that allows more exposure at high levels.

What values do I need to enter?

This calculator takes 4 inputs: Measured sound level, Exposure duration, Criterion level, Exchange rate. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.