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Outdoor Noise Barrier Calculator

Calculate sound barrier insertion loss using the Maekawa method with Fresnel number analysis for outdoor noise barriers.

Inputs

Results

Insertion loss (dB)

14.74

Fresnel number (N)1.34
Path difference (m)0.46
Wavelength (m)0.69
Effective barrier height (m)2.5
How to Use This Calculator
  1. Enter Barrier height (m), Source to barrier (m), and Barrier to receiver (m).
  2. Set Source height (m), Receiver height (m), and Frequency (Hz).
  3. Review the Insertion loss (dB) result.
  4. Use Fresnel number (N) and Path difference (m) to inform your decision.

How the result changes with Barrier height (m)

Barrier height (m)Insertion loss (dB)
2.0911.44
7.0622.45
1324
1824

What each input means

Barrier height (m)
Height of the noise barrier above ground level in meters.
Source to barrier (m)
Horizontal distance from the noise source to the barrier in meters.
Barrier to receiver (m)
Horizontal distance from the barrier to the receiver in meters.
Source height (m)
Height of the noise source above ground level (0 for ground-level sources).
Receiver height (m)
Height of the receiver above ground (typically 1.5 m for ear height).
Frequency (Hz)
Sound frequency in Hz. Higher frequencies are blocked more effectively.

What each result means

Insertion loss (dB)
Sound reduction provided by the barrier using the Maekawa formula (max ~24 dB for single barrier).
Fresnel number (N)
Dimensionless number characterizing diffraction; higher N means more attenuation.
Path difference (m)
Difference between the diffracted path over the barrier and the direct path.
Wavelength (m)
Wavelength of the sound at the specified frequency.
Effective barrier height (m)
Height of the barrier above the line of sight between source and receiver.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Barrier height (m) = 3, Source to barrier (m) = 10, Barrier to receiver (m) = 20, Source height (m) = 0 = 6 input(s) provided
  2. Calculate Insertion loss
    Insertion loss
    14.74 = 14.74
  3. Calculate Fresnel number
    Fresnel number = (2 * delta) / wavelength
    1.338 = 1.338
  4. Calculate Path difference
    Path difference = diffractedPath - directPath
    0.459 = 0.459

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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