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Acoustic Fence Calculator
Calculate acoustic barrier panels and noise reduction based on panel mass, height and noise source geometry. UK specifications and dB ratings.
Total run of acoustic barrier
Taller = better noise reduction
Height above ground (e.g. car exhaust ~0.5m). Fence must rise above this to break line of sight.
From fence to noise source
From fence to listener position
Your supplier's price per acoustic panel
Standard: 1.83m (6ft). Post spacing matches panel width.
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How We Calculate This
This calculator estimates the acoustic fence panels needed and the likely noise reduction. It combines two things: a panel-class figure for the barrier’s typical effective insertion loss (set by its surface mass), and a geometry adjustment from Maekawa’s barrier-diffraction curve based on how well the fence breaks the line of sight between source and listener.
The method
Panels = Fence length ÷ Panel width (rounded up)
Panel rating = effective insertion loss by mass class (12–30 kg/m² → ~15–28 dB)
Path difference δ = A + B − d (source→top + top→receiver − direct path)
Geometry shift: IL = 10 × log₁₀(3 + 20N), Fresnel number N = 2δ÷λ (Maekawa 1968)
The panel-class figures are indicative real-world effectiveinsertion loss. They sit below headline lab ratings (measured to BS EN 1793-2) because field geometry, ground reflection and flanking erode lab performance — for example Jacksons Jakoustic Reflective (25 kg/m²) is rated 28 dB in the lab, and Forest Decibel panels up to 30 dB. The underlying physics is the mass law (true form TL ≈ 20 × log₁₀(m × f) − 47 dB), under which doubling the surface mass adds roughly 6 dB — so heavier panels give progressively more reduction, but with diminishing returns.
Crucially, a fence only attenuates noise once it breaks the line of sight (its top rises above the source→listener sight line, δ > 0). If the source is at or above the fence top, Maekawa’s curve gives ~0 dB of diffraction benefit and this calculator reports little reduction.
Key considerations
- No gaps — even small gaps drastically reduce acoustic performance
- Height should break line of sight to the noise source
- Heavier panels provide better low-frequency noise reduction
- Ground conditions affect reflected noise paths
Frequently Asked Questions
Acoustic fences typically reduce noise by 15-28 dB depending on the panel mass and construction. A standard acoustic panel (12 kg/m²) provides around 15 dB reduction, while premium panels (25 kg/m²) can achieve 25 dB or more. For reference, a 10 dB reduction sounds roughly half as loud to the human ear.
Fence height is critical for acoustic performance. The fence must break the line of sight between the noise source and the listener to be effective — below that, it does almost nothing. Once the line of sight is broken, taller fences give more diffraction attenuation, but with diminishing returns: as a rule of thumb each doubling of the path difference (roughly, of the effective height above the sight line) adds only about 3 dB. Most acoustic fences are 2-3m tall.
Acoustic fences use dense, tongue-and-groove or overlapping boards with no gaps. The panels are typically 20-40mm thick with a mass of 12-30 kg/m². Standard fence panels have gaps and lightweight construction that allow sound to pass through. Acoustic panels may include mass-loaded vinyl or mineral wool cores for extra performance.
In England, fences up to 2m do not usually require planning permission unless on a highway boundary (1m limit). For acoustic fences over 2m, planning permission is typically required. Some local authorities have specific policies on noise barriers. If the fence is part of a planning condition, you must comply with the specified acoustic requirements.
For maximum noise reduction, position the acoustic fence as close to the noise source as possible, or as close to the receiver as possible. The worst position is midway between the two. To stop noise flanking around the ends, the barrier should be long enough that the distance from the listener to each barrier end is at least 4 times the perpendicular distance from the listener to the barrier (the FHWA Noise Barrier Design Handbook '4× rule'). A barrier that is too short can lose up to 5 dB(A) of its design performance for receivers near the ends.
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Last updated: March 2026
Verified against UK standards · estimates only, confirm with your supplier.