Inverse Square Law for Sound Explained
When this applies
Use this guide for free-field estimates where reflections and room modes are not yet dominating the result.
Tool to use
Browser-based preliminary check for Inverse Square Law Sound Calculator — fast estimates, not code or stamped design output.
Open Inverse Square Law Sound Calculator →Steps
- 1Confirm whether the source approximates a point source for the distances you care about.
- 2Measure or estimate reference level at a known distance.
- 3Apply inverse-square level change when doubling distance is far compared to source size.
- 4Document that indoor spaces break the assumption via reflections and absorption.
- 5Escalate to room acoustics models when reverberation or openings matter.
Examples
- Outdoor machinery noise rough check for fence line discussions.
- Temporary event speaker placement what-if.
What to avoid
- Using inverse square inside reverberant rooms without qualification.
- Forgetting that dB already implies log scaling when mixing formulas.
- Ignoring directivity and wind for large industrial sources.
Related tools
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Browse all task guides or see the full list on the Engineering hub.
FAQ
Does this include atmospheric absorption?
No. It is geometric spreading only.
Line sources?
Cylindrical spreading differs; use dedicated line-source guidance when appropriate.