What the software produces is reference data

Why measured results will differ

These are the things that decide a measurement and that the calculation cannot see. None of them is a fault in the calculation; they simply sit outside its scope.

• What the surface is actually built from

  It may all be called “plasterboard”, but one layer or two, how deep the cavity is, whether there is mineral wool inside it — those three change the absorption coefficient at 125 Hz by several times over. The figures in the catalogue are table values for a typical build-up, not for the wall in your building.

• What is in the room

  Seats, curtains, rugs, the equipment rack and the audience themselves all absorb sound. The tool counts what has been entered; it cannot count the rest.

• Leakage and background noise

  Door gaps, service risers, HVAC grilles, the fans in the projector and the amplifiers. The real noise floor sets the dynamic range you can hear, and it can only be measured with every piece of equipment running at operating temperature.

• Equipment tolerances

  Catalogue figures are datasheet figures. Two speakers of the same model still differ within manufacturing tolerance, and published sensitivity is usually measured anechoically rather than in your room.

• Installation variance

  A speaker mounted a few centimetres off, panels that do not sit tight against each other, a baffle cavity that is not sealed, a riser finished in a different material from the one specified — a little from each, and they add up.

• Projectors dim over time

  Light output falls with lamp or laser hours, and real brightness also depends on picture mode, zoom position and dust on the screen. The tool already applies a real-world efficiency factor, but that factor is itself an estimate.

• The measurement has its own error

  Microphone type, where the microphone sits, how the curve is smoothed — change any one of the three and the measured number changes with it. Two people measuring the same room can come away with two different results.

• Rooms that are not rectangular

  RP22 §7.3.1 states plainly that non-rectangular rooms are extremely difficult to model, so rules-based recommendations are impossible. The tool still draws and calculates on the floor plan you traced, but the ranking of subwoofer layouts no longer guarantees anything there — and the tool warns you at exactly that point.

What we do and do not guarantee

We guarantee that the calculations follow the formulas and thresholds of the documents we name, and that every number traces back to its source. If you find a result that disagrees with the document, tell us — that is a bug, and we fix it.

We do not guarantee that measurements taken on site will match the results in the software. For the reasons above, the two figures almost always differ to some degree, and how far apart they land depends on things outside the reach of the calculation.

Nor do we guarantee that a design reaching a given Performance Level in the software will be signed off at that level in the real room. Sign-off has to rest on measurements taken on site.

Responsibility for what you do with the results

Results from the software are there to support your design work and your conversations with clients. They do not replace a design submission signed by someone accountable for it, they do not replace measurement and sign-off, and they do not replace the judgement of a qualified person on that particular job.

Every construction, purchasing and quoting decision made on these results belongs to whoever is using them. Before committing to a client, check the equipment figures against the manufacturer’s current datasheet, and check the assumptions about surface build-up against what is really there.

Equipment data in the catalogue

Equipment figures are normalised from the manufacturer’s technical documentation. Wherever a value is an estimate or a typical figure for its class rather than a published one, the interface marks it right there, and the Reference documents section lists every such case.

Prices, availability and product revisions change over time. The bill of materials and the quotation the software exports are a draft for you to check and adjust, not a binding offer.

Changes to these terms

Formulas, thresholds and data in the software are updated when a source document is updated or when we add a new source. A design saved earlier and reopened afterwards may be scored differently — that is deliberate, because the version worth trusting is the current one.

This page changes along with those updates. The version you are reading is the one in force.