Noise Barrier Height Calculator

Work out noise barrier height instantly with clear inputs, formula shown and shareable results.

About Noise Barrier Height Calculator

A noise barrier works by forcing sound to diffract over its top, lengthening the path. The Fresnel number, based on the extra path length, determines insertion loss. Breaking the line of sight gives about 5 dB; each doubling of the effective height above the sight line adds roughly 3 dB, with 10-15 dB a practical maximum.

Formulas

Path difference

delta = source-to-top + top-to-receiver - direct distance

Fresnel number and insertion loss

N = 2 delta / wavelength; IL = 5 + 20 log10(sqrt(2 pi N) / tanh(sqrt(2 pi N)))

Worked example

With the default values below, Noise Barrier Height Calculator returns Recommended Barrier Height of 2.50. Change any input above and every figure here is recalculated in your browser.

Inputs used

Source Heightminimum 0 m: 1 m
Receiver Heightminimum 0 m: 1.5 m
Source To Barrier Distanceminimum 0 m: 10 m
Barrier To Receiver Distanceminimum 0 m: 30 m

Results

Recommended Barrier Height: 2.50
Insertion Loss Achieved: 11.895
Sight Line Height At Barrier: 1.125
Height Options Evaluated: 27

Step by step

1Values used
2Path difference
3Fresnel number and insertion loss
4Recommended Barrier Height= 2.50
5Insertion Loss Achieved= 11.895
6Sight Line Height At Barrier= 1.125
7Height Options Evaluated= 27

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Noise assessment for planning or permitting must follow the applicable standard with measured or modelled source levels. Barrier design should be verified by an acoustic consultant.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Noise assessment for planning or permitting must follow the applicable standard with measured or modelled source levels. Barrier design should be verified by an acoustic consultant.

Frequently Asked Questions

Why is 15 dB a practical limit?

Because sound diffracts around the ends of the barrier and reflects off other surfaces, so beyond about 15 dB those flanking paths dominate and further height gains nothing.

Does barrier material matter?

Only that it is sufficiently massive and has no gaps — typically 10 kg/m2 or more. Absorptive facing helps only where reflections between parallel barriers are a problem.