Every figure, checked against something real.
Every AcoustaPLOT report states plainly which standard its figures are being compared against. Here's what each one actually covers, where it's used in your report, and what it doesn't claim to do.
One calculates the noise. One calculates the fence.
Calculation of Road Traffic Noise
Road noise, wherever a property sits outside Defra's mapped coverage
Where a property's road noise falls within Defra Strategic Noise Map coverage, that's read directly as the primary source. Elsewhere, CRTN 1988 is applied to Department for Transport AADF traffic-count data and converted to Lden and Lnight. Defra and CRTN are never both used for the same source: it's one or the other. This method covers road noise only -- railway noise outside Defra's coverage uses CRN 1995 instead, see below.
Calculation of Railway Noise
Railway noise, wherever a property sits outside Defra's mapped coverage
Where a property's railway noise falls within Defra Strategic Noise Map coverage, that's read directly as the primary source. Elsewhere, CRN 1995 is applied to the nearest track's estimated service pattern and converted to Lden and Lnight -- the dedicated railway-noise method, not CRTN's road-traffic calculation reused for rail. Where a property has a result from both road AND rail (from either source, mapped or calculated), those two separate exposures are combined by logarithmic energy addition into one overall figure. Where there is no nearby railway at all, no rail figure is produced -- the report simply reflects road noise alone rather than guessing at a railway exposure that doesn't apply.
Attenuation of sound during propagation outdoors
Acoustic Barrier Design — every recommended fence height, length and return
A terrain cross-section from real elevation data feeds an octave-band calculation of divergence, atmospheric absorption, ground effect and barrier diffraction under ISO 9613-2 §7.4. The standard's own single-ray, infinite-fence method is kept as a reference figure for long highway-scale schemes, but it overstates what a finite domestic garden fence actually achieves — so the height and return length AcoustaPLOT recommends instead integrate along the road as a line source and account for diffraction around the ends of the fence, not just over the top of it. ISO 9613-2's own diffraction term is used throughout, not the older Maekawa nomograph some consultants still convert from; where the two would diverge, the figure never recommends a lower barrier than the Maekawa convention would.
Four references, one number.
Every risk band on a report is set against more than one line of guidance, not a single arbitrary cutoff — a UK planning benchmark, the international health guidance it sits alongside, and the primary dataset it's read from.
Guidance on sound insulation and noise reduction for buildings
The indoor-estimate comparison on every report
The reference point every report's indoor-noise estimate is measured against, alongside the Noise Policy Statement for England.
Noise Policy Statement for England
The SOAEL/UAEL thresholds behind AcoustaPLOT's risk bands
NPSE itself sets out three effect levels: No Observed Effect Level (NOEL), Lowest Observed Adverse Effect Level (LOAEL) and Significant Observed Adverse Effect Level (SOAEL) -- but deliberately does not publish fixed dB figures for any of them, leaving that judgement to be made case by case. ‘UAEL’ (Unacceptable Adverse Effect Level) is not an NPSE term at all -- it is AcoustaPLOT’s own further category above SOAEL, not a fourth level the government document defines. The 63 dB (SOAEL proxy) and 69 dB (UAEL) figures stated on the Methodology page are both AcoustaPLOT’s own screening thresholds, set by a professionally qualified acoustician rather than government numbers, informed by NPSE’s framework and applied consistently across our seven risk bands rather than an arbitrary scale.
Environmental Noise Guidelines for the European Region
The reference threshold shown against every road-noise result
The World Health Organization's road-noise guideline of 53 dB Lden is quoted on every report alongside the England-specific SOAEL/UAEL proxies, so a result can be read against both a UK planning benchmark and the wider international health guidance in the same place.
Strategic Noise Mapping, Environmental Noise Directive, Round 4 (2022)
The primary data source for Noise Risk Screening wherever it has coverage
Defra's own modelled road and railway noise bands, from the most recent (2022) mapping round, are read directly wherever a property falls within their coverage — this takes precedence, per category, over the CRTN-based calculation above, which exists specifically to cover the gaps this mapping doesn't reach for that category.
Full risk-band thresholds and every dataset used are on the Methodology page.
A standard tells you what was checked. This tells you what wasn't.
Standards describe the method. They don't describe what a modelled report can and can't stand in for — so every AcoustaPLOT report, and every tier on the pricing page, carries the same five lines, unchanged, next to the price and the buy button:
- ✓Automated and modelled — produced by our software from national datasets, not measured at your property.
- ✓No site visit and no individual human review of your report.
- ✓Every report states its uncertainty range. Figures are estimates within that range.
- ✓Not suitable as the sole or primary evidence for a planning application or appeal, legal proceedings, an insurance claim, or anything else needing a precise measured level.
- ✓In a purchase or price negotiation it is supporting context for your own decision — not a valuation, and not a measured figure the other side has to accept.
Want the full data sources, risk-band table and declared limitations behind these figures?