KEVOS® MAKEOS · Engineering
Noise Exposure Check (Combined Sources, Distance, Dose)
What sound level does the operator get from these machines at their working position, and is their daily noise dose within the limit?
Workplace noise exposure from up to four sources: levels combined by logarithmic addition (as the sound level tool, sum mode), reduced from the reference distance to the operator distance by the inverse-square law (as the distance mode), background noise added, the permitted time at that level from your criterion level, criterion time and exchange rate, the daily dose for the hours exposed and the equivalent eight-hour level.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Source 1 level at the reference distance | dB | Sound level of the first machine measured at the reference distance. |
| Source 2 level (0 = none) | dB | Second machine (0 if not used). |
| Source 3 level (0 = none) | dB | Third machine (0 if not used). |
| Source 4 level (0 = none) | dB | Fourth machine (0 if not used). |
| Reference distance of the source levels | m | Distance at which the source levels were measured. |
| Operator distance from the sources | m | Distance from the sources to the operator’s ear (all sources taken at this distance). |
| Background level at the operator | dB | Background level at the operator from everything else. |
| Hours exposed per day | h | Hours per day the operator spends at this position. |
| Criterion level | dB | Exposure limit level for the criterion time (from your regulation; often 85 dB(A)). |
| Criterion time | h | Time the criterion level may be worn (usually 8 h). |
| Exchange rate | dB | Exchange rate: level change that halves or doubles the permitted time (3 dB in most of the world, 5 dB in some US rules). |
Method and formulas
- Combined level L = 10 log₁₀ Σ 10^(Lᵢ ÷ 10) (as the sound level tool, sum mode).
- At the operator L₂ = L − 20 log₁₀(r₂ ÷ r₁) (as the distance mode); then add the background logarithmically.
- Permitted time = T_c ÷ 2^[(L − L_c) ÷ ER]; dose = hours ÷ permitted time.
- Equivalent level for the criterion time = L_c + ER × log₂(dose).
- Example: the machines combine to 91.193 dB; at 3 m the operator gets 81.938 dB, a 49.29% daily dose.
Limitations
- Point sources in open space: reflections in a room raise levels above the inverse-square estimate.
- Use A-weighted levels; impulse noise needs a peak check.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check whether an operator needs hearing protection
- See how far to move a workstation from noisy machines
- Estimate dose for a shift pattern
Who it is for
- Safety officers
- Plant engineers
- Production supervisors
What you get
- Combined level at the sources and at the operator
- Permitted time and daily dose
- Equivalent eight-hour level
Interpreting the result
- Every doubling of distance lowers a point source by about 6 dB, a quarter of the dose at a 3 dB exchange rate.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3455–3456. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Noise Exposure Check (Combined Sources, Distance, Dose) calculator
