Sound Distance Attenuation
Calculator
Results
- Level at the target distance (dB)
- 80
- Attenuation (dB)
- 20
- Distance ratio
- 10
Music and audio results
| Level at the target distance (dB) | 80 |
| Attenuation (dB) | 20 |
| Distance ratio | 10 |
formula-map diagram
- Level at the target distance (dB)
- 80
- Attenuation (dB)
- 20
- Distance ratio
- 10
Musical and acoustic relationship
Formula
L₂ = L₁ − 20 × log₁₀(d₂ ÷ d₁)= 80
Note
This result is a simplified model: it applies the displayed standard formula to the values you entered, assuming twelve-tone equal temperament, a speed of sound of 343 m/s in dry air at 20 °C, an ideal free field with no reflections or air absorption, purely resistive speaker loads and Sabine's diffuse-field assumption. Real rooms, instruments, codecs and amplifiers depart from these idealisations, so measure with proper instruments for critical work.
More in Music and audio
See all →Frequently asked questions
How does sound level drop off with distance?+
For a point source in open air, sound pressure level follows the inverse square law, dropping by about 6 dB every time the distance from the source doubles. The calculator applies dB = 20 x log10(d1/d2) to find the level change between two distances.
Why 6 dB per doubling of distance and not some other number?+
Sound energy spreads out over an expanding spherical surface as it travels, and that surface area grows with the square of the distance, so intensity falls proportional to 1/distance². Converting that squared relationship to decibels (using the 20 x log10 factor for amplitude-like quantities) yields the well-known 6 dB figure.
Does this rule apply indoors as accurately as outdoors?+
No, the 6 dB per doubling rule assumes free-field conditions with no reflections, so indoors, reflections off walls and ceilings reduce the actual drop-off, often to something closer to 3-4 dB per doubling in a reverberant room. The calculator gives the theoretical free-field figure, which is a starting estimate rather than a guarantee for enclosed spaces.
How is this useful for setting up a PA system or speakers?+
Knowing the attenuation rate lets you estimate how loud a speaker will sound at a listener's actual distance versus its rated output at a reference distance (often 1 meter), which helps avoid under- or over-powering an audience area. It's also key for community noise compliance, estimating how much a source will have quieted down by the property line.
Why does doubling the distance again (from 20m to 40m) not sound like it drops as much as the first doubling?+
Each doubling always removes the same 6 dB regardless of the starting distance, but human loudness perception is itself logarithmic, so the absolute Hz or dB numbers can feel like they matter less at greater distances even though the physics is perfectly consistent. The dB drop per doubling never changes; only how noticeable it feels does.