Atenuação por distância
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The 'Attenuation by Distance' calculator determines the reduction in sound level (in decibels, dB) as the sound source moves closer or farther. The formula ΔL = 20·log(d₂/d₁) calculates sound level variation based on the ratio of two distances (d₁ and d₂). It's essential in acoustic projects, such as positioning speakers or predicting noise barrier impacts.
Attenuation happens because sound intensity decreases proportionally to the square of the distance. The formula uses a logarithm to convert this nonlinear relationship into a linear decibel scale, enabling perceptible volume changes in civil engineering, architecture, or industrial noise analysis.
Use this calculator in open spaces without obstacles affecting sound propagation. Note: it doesn't account for material absorption, temperature, or physical barriers. Results are valid only for pure distance comparisons, not for complex noise pollution calculations.
Frequently asked questions
How does the formula ΔL = 20·log(d₂/d₁) work in practice?
It calculates sound level variation (in dB) based on the ratio of two distances. For example, doubling the distance reduces the sound level by ~6 dB.
When to use this calculator in construction projects?
To predict noise attenuation in open spaces or adjust speaker positioning in audio systems.
Does the calculator account for obstacles between the source and receiver?
No. It assumes free space. Obstacles like walls or vegetation need separate analysis.
Can I use units other than meters?
Yes, as long as both distances are in the same unit (meters, feet, etc.).
Is the result accurate for noise pollution calculations?
No. The formula ignores material absorption and reflections, which are common in real-world environments.