Physics

Distance Attenuation Calculator

Find how much a sound level drops with distance.

Level at reference (dB)

Reference distance

New distance

Calculated Output

Level at new distance (dB) 70

Formula: L₂ = L₁ − 20·log₁₀(d₂ ÷ d₁)

Step-by-Step Breakdown

1. Values used:

2. Level at reference = 90 dB

3. Reference distance = 1

4. New distance = 10

6. Level at new distance = 70dB

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The math behind it

For a point source, L₂ = L₁ − 20·log₁₀(d₂/d₁). Each doubling of distance drops the level by about 6 dB.

90 dB at 1 m → 70 dB at 10 m.

Why 6 dB per doubling?

The inverse-square law spreads power over four times the area, a factor of 4 (≈6 dB).