Acoustic Power Calculator Formula

Understand the math behind the acoustic power calculator. Each variable explained with a worked example.

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Formulas Used

Sound Power Level

power_level = 10 * log10(power / 1e-12)

Intensity at 1 m (free field)

intensity_1m = power / (4 * pi * 1)

Variables

VariableDescriptionDefault
powerSound Power(W)0.01

How It Works

Sound Power Level

Sound power is the total acoustic energy emitted by a source per second, independent of distance or room.

Formula

Lw = 10 log10(W / W0)

  • *W* = sound power (watts)
  • *W0* = 10^-12 W (reference)

    • Sound power is an intrinsic property of the source. Intensity at distance r in free field: I = W / (4 pi r^2).

    Worked Example

    A loudspeaker emitting 0.01 W.

    power = 0.01
    1. 01Lw = 10 log10(0.01 / 1e-12)
    2. 02Lw = 10 log10(1e10)
    3. 03Lw = 10 * 10 = 100 dB
    4. 04Intensity at 1 m = 0.01 / (4 pi) = 7.96e-4 W/m2

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