Speaker SPL
Calculate the sound pressure level (dB SPL) of a speaker at a distance from its sensitivity (dB @1 W/1 m) and the applied power, or solve for the power or the distance needed for a target SPL. Free-field model (no reverberation), with −6 dB per doubling of distance. Everything in your browser.
SPL by distance
| Distance | SPL | vs 1 m |
|---|
current distance · every time the distance doubles the level drops 6 dB.
How it is calculated · SPL, power and distance
1. Free-field SPL at distance
d (in meters):
SPL = sensitivity + 10·log₁₀(P) − 20·log₁₀(d), with
P in watts. Sensitivity is the SPL at
1 W and 1 m.
2. Power: each doubling gives
+3 dB → 10·log₁₀(P). Distance: each
doubling subtracts −6 dB → −20·log₁₀(d)
(inverse-square law).
3. Solve the power for a
target SPL at distance d:
P = 10^((target − sens + 20·log₁₀(d)) / 10).
4. Solve the distance for
a target SPL at power P:
d = 10^((sens + 10·log₁₀(P) − target) / 20).
5. Free-field model (outdoors or an anechoic chamber): it ignores reverberation, room reflections and air absorption. Indoors the real SPL is usually higher because of reflections. It does not account for the speaker's distortion or its maximum power handling.
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