Fact · Dictation
6decibels per doubling of distance
Under ideal conditions with no reflections or background sound, a sound level drops by 6 dB for every doubling of the distance from the source.
Checked against its source on October 16, 2026
In the source's own words
“The general rule of thumb is that, under ideal conditions (no reflecting surfaces or other background sound or interference), a sound level drops 6 dB for every doubling of the distance from the source.”
Inverse-Square Law (Sonic Studio Acoustics Handbook), Simon Fraser University, Sonic Studio, Simon Fraser University, Sonic Studio acoustics handbook, n.d., Inverse-Square Law section.
Open the original- What it measures
- A university acoustics handbook. It describes sound from a point source spreading out with the square of distance, which gives the 6 dB figure as a rule of thumb.
- What it does not show
- The rule assumes a point source in a free field with no reflections or background sound. Real rooms, reflections and close-up microphones do not follow it exactly, and the drop near a close microphone can be larger.