Noise Pollution Calculator — Sound Level at Distance
Enter the sound level at a known distance, choose point or line source geometry, and get the predicted decibel level at any target distance — plus the WHO community risk rating and NIOSH maximum daily exposure time.
dB
m
m
Source type
Predicted level using inverse-distance attenuation
- 1
Distance ratio d₂ ÷ d₁
50 ÷ 10 = 5 - 2
log₁₀(ratio)
log₁₀(5) = 0.699 - 3
Attenuation (20 × log₁₀)
20 × 0.699 = 13.98Point source: 20 dB per decade of distance. - 4
Sound level at target distance
80 − 13.98 = 66
How does this calculator work?
Point-source noise drops 20 × log₁₀(d₂/d₁) dB with distance; line sources (roads) drop only half that. WHO recommends community noise below 53 dB LAeq,day; NIOSH limits occupational exposure to 480/2^((L−85)/3) minutes at L dB. Use this calculator to predict levels at any distance and check health risk.
Formula
How this is calculated
Sound intensity from a point source (a machine, a vehicle, an air-conditioning unit) spreads over an ever-larger spherical surface as distance increases, causing the sound pressure level to drop 6 dB every time the distance doubles — mathematically: L₂ = L₁ − 20 × log₁₀(d₂/d₁). A true line source, such as a long straight highway or railway, spreads only cylindrically, giving a softer roll-off of 3 dB per doubling of distance: L₂ = L₁ − 10 × log₁₀(d₂/d₁). Real-world attenuation also includes air absorption (significant above 500 Hz over long distances), ground reflection, and barriers, none of which are included here — so treat these results as free-field estimates.
The WHO Environmental Noise Guidelines for the European Region (2018) recommend limiting road traffic noise to 53 dB LAeq,day and 45 dB LAeq,night for communities, and 45 dB for railway and aircraft noise. Levels above 65 dB are associated with cardiovascular disease risk. The NIOSH recommended exposure limit uses a 3 dB exchange rate: permissible daily exposure = 480 / 2^((L−85)/3) minutes, halving with every 3 dB increase above 85 dB.
All dB values are A-weighted (dBA) community or occupational averages in practice; this calculator treats the entered value as already being an appropriate average. For accurate assessment, measure with a calibrated sound level meter and compute Leq over a representative period.
Frequently asked questions
A point source spreads in a sphere (area ∝ d²), giving −6 dB per doubling. An infinite line source spreads cylindrically (area ∝ d), giving only −3 dB per doubling. A long road is a practical line source, so it attenuates more slowly than a stationary machine.
NIOSH recommends that the permissible daily exposure time halves with every 3 dB increase in sound level above 85 dB. So 88 dB → 4 h, 91 dB → 2 h, 94 dB → 1 h. OSHA uses a 5 dB exchange rate (less protective), giving longer limits at the same level.
Doubling the distance from a point source cuts approximately 6 dB. Noise barriers (solid fences, earth berms) can add 10–15 dB attenuation depending on height and transmission loss. Acoustically absorptive surfaces and traffic calming (speed, volume) reduce the source level directly.
Also known as
TG we-Calculate Editorial Team. (2026). Noise Pollution Calculator — Sound Level at Distance [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/noise-pollution-calculator
TG we-Calculate Editorial Team. "Noise Pollution Calculator — Sound Level at Distance." TG we-Calculate. 2026. https://we-calculate.com/calculator/noise-pollution-calculator.
TG we-Calculate Editorial Team, "Noise Pollution Calculator — Sound Level at Distance," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/noise-pollution-calculator
@misc{wecalculate_noise_pollution_calculator, title = {Noise Pollution Calculator — Sound Level at Distance}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/noise-pollution-calculator}}, year = {2026}, note = {TG we-Calculate} }
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