Sound Attenuation⚠ unverified
Physics / Acoustics · Compute the attenuation of sound due to atmospheric absorption
Parameters
| Input | Symbol | Unit | Default | Description |
|---|---|---|---|---|
| distance | distance | m | 1.0 | Propagation distance |
| alpha | α | dB/m | 1.0 | Attenuation coefficient |
| Output | Symbol | Unit | Description |
|---|---|---|---|
| result | attenuation | dB | Total attenuation, in decibels (dB) |
The science & history
Understanding the Parameters
-
$\alpha$ — depends on frequency, humidity, temperature (ISO 9613 atmospheric absorption) or lining material in ducts.
-
$d$ — longer paths accumulate more dB loss.
- Output — additive in dB: $L(d) = L(0) - \alpha d$ (plus spreading if applicable).
Derivation (Approaching a Proof)
If intensity decays exponentially $I = I_0 e^{-\gamma x}$, the level change is proportional to $x$. Defining $\alpha$ in dB/m so that $\Delta L = \alpha x$ is the engineering statement of that exponential absorption. Spreading in spherical waves is a separate geometric factor.
History
Atmospheric absorption tables and duct liner data are standard outdoor and HVAC noise tools.
Related Concepts: Sound Pressure Level, Insertion Loss, Sound Intensity
Notes: Registry calculator sound-attenuation (unverified). Linear $\alpha d$ only — no spreading.