Resources
Everything here exists because someone asked us the same question more than once. Which standard does my specification actually mean, what will the report say, and why does the number I was given not match the one I measured.
Why we publish this rather than a blog
There is no shortage of articles explaining what sound absorption is. Anyone can get that answer in seconds now, and writing another one adds nothing. What cannot be produced without owning the rooms and doing the physical work is the practical detail: which standard a given specification really requires, what a specimen has to look like before it can be tested, how much two laboratories can legitimately differ, and what changes a result more than people expect.
So that is what goes here. A standards reference with a page for each standard stating plainly whether it falls inside our accredited scope, and laboratory notes recording what we actually observe.
The three questions that come up most
My specification names a standard I cannot find. What now?
Send us the clause. Specifications routinely name withdrawn editions — the ISO 140 series is the common one, superseded by ISO 10140 — or name an ISO standard where the market in practice expects the ASTM equivalent. We will tell you what it means before you commit to a test.
Why does my result differ from the supplier's published figure?
Usually the mounting condition, occasionally the standard, sometimes both. The same absorber tested direct to a rigid backing and with a 200 mm air gap can differ by several tenths of an absorption coefficient at low frequency. A figure quoted without its mounting condition is not comparable to anything.
Is this standard inside your accredited scope?
Every standard page answers that in the first screen. Three calibration services are accredited under certificate 24-LB0054 — sound level meters, sound calibrators and measurement microphones. Everything else is traceable but outside the scope, and we say so on the certificate as well as on the site.
Standards
What each standard requires, what sample we need, which room does it, and whether it is in our accredited scope.
Laboratory notes
What we observe doing this work — the things you only learn by putting samples in rooms.
Field check or calibration?
A calibrator checks one level at one frequency. What periodic testing to IEC 61672-3 covers that it does not, and when the difference gets challenged.
What is calibration
Traceability, uncertainty and what a certificate does and does not tell you.