It is the question that decides whether your report costs $600 or $1,600. The honest answer depends on one thing: whether the
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September 06, 2026
Do you need a noise survey, or will a desk assessment do?
By
September 06, 2026
It is the question that decides whether your report costs $600 or $1,600. The honest answer depends on one thing: whether the assessment has to compare against a measured background sound level.
When a survey is genuinely required
A full BS 4142 assessment compares the rating level of your plant against the background sound level at the nearest home. The standard expects that background to be measured — typically as an LA90 over a representative period, often overnight, because night is the hardest case.
If your planning officer or environmental health officer has explicitly asked for measured background data, no amount of desk work substitutes for it. You either commission a local acoustician to measure it, or you supply data from a previous survey.
When a desk assessment is the right answer
Plenty of acoustic work does not depend on measurement at all:
- Sound insulation design — specifying wall and floor build-ups is a calculation against published performance data. A site visit adds nothing.
- Room acoustics — reverberation is calculated from room volume and surface finishes. Dimensions and photographs are enough.
- Glazing and ventilation specification — the most commercially useful output of a residential noise assessment, and unaffected by whether the input levels were measured or derived.
- Screening assessments — early design work, where you need to know whether there is a problem before spending on a survey.
The middle ground, and how to handle it honestly
Many residential sites can be assessed from published sources: strategic noise mapping, traffic flow data, rail timetables. This is legitimate and widely accepted — provided the report says clearly what data it used and what that means for confidence.
What is not acceptable is a report that presents derived levels as though they were measured. That is the kind of thing that gets a scheme refused and a consultant remembered.
How we handle it
We are desk-based and we do not measure. So we do two things: we tell you before you order if we think a survey is unavoidable, and where we produce a screening assessment we label it as one, in the report title.
If you already have survey data, several of our tiers are built around exactly that — send the measurement report and calibration records and we produce a full assessment.