Noise Level Calculator
Measure and compare noise levels in decibels for construction sites, evaluating combined sources and distance attenuation for safety compliance.
Formula
L2 = L1 - 20 x log10(d2/d1) - Barrier Reduction
Sound level at a new distance equals the known level minus 20 times the base-10 logarithm of the distance ratio, minus any barrier attenuation. This inverse square law applies to point sources in free field conditions. For combining sources: Ltotal = 10 x log10(10^(L1/10) + 10^(L2/10)).
Worked Examples
Example 1: Equipment Noise at Property Line
Problem: An excavator produces 95 dBA at 3 meters. What is the noise level at a property line 30 meters away?
Solution: L = 95 - 20 x log10(30/3)\nL = 95 - 20 x log10(10)\nL = 95 - 20 x 1.0 = 75 dBA
Result: 75 dBA at the property line, 20 dB attenuation from distance
Example 2: Two Sources Combined
Problem: Two generators produce 85 dBA and 88 dBA at a worker location. What is the combined level?
Solution: L = 10 x log10(10^(85/10) + 10^(88/10))\nL = 10 x log10(3.162x10^8 + 6.310x10^8)\nL = 10 x log10(9.472x10^8) = 89.8 dBA
Result: 89.8 dBA combined level (not simply 85 + 88 = 173)
Frequently Asked Questions
How does sound level decrease with distance?
Sound levels decrease according to the inverse square law. For a point source in open air, the level drops by 6 dB each time the distance from the source is doubled. This is expressed as L2 = L1 - 20 x log10(d2/d1). At 10 meters from a 100 dB source measured at 1 meter, the level would be approximately 80 dB. Soft ground, barriers, and atmospheric absorption can cause additional attenuation beyond this basic calculation.
How do you combine noise levels from multiple sources?
Sound levels in decibels cannot be simply added because decibels are logarithmic. To combine two sources, convert each to sound intensity using 10^(dB/10), add the intensities, then convert back using 10 x log10(total). As a quick rule: two equal sources add 3 dB (e.g., two 90 dB sources together produce 93 dB). If one source is 10 dB or more below the other, the quieter source has negligible effect on the combined level.
What noise levels are typical on construction sites?
Common construction equipment produces the following noise levels at the operator position: jackhammers 100-110 dBA, concrete saws 100-105 dBA, excavators 85-95 dBA, pile drivers 95-110 dBA, generators 80-95 dBA, and hand tools 85-100 dBA. Background noise on an active construction site typically ranges from 80-95 dBA. Proper noise assessments should measure actual levels rather than relying on generic values.
How effective are noise barriers on construction sites?
Temporary noise barriers typically provide 5-15 dB of attenuation depending on their height, material density, and positioning relative to source and receiver. A solid plywood barrier reduces noise by about 10 dB, while acoustic blankets on chain-link fencing provide 8-12 dB reduction. Barriers are most effective when placed close to either the source or receiver, and when they are tall enough to break the line of sight between the two.
Can I use the results for professional or academic purposes?
You may use the results for reference and educational purposes. For professional reports, academic papers, or critical decisions, we recommend verifying outputs against peer-reviewed sources or consulting a qualified expert in the relevant field.
Is Noise Level Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.