Office pod acoustic rating: what dB reduction numbers really mean
An office pod acoustic rating is the one specification every brand advertises and almost none of them explain. You will see 28 dB on one brochure and 34 dB on another with no indication of what was measured, under which standard, or in which configuration — and a decibel figure without those three things attached is not a specification, it is a number. This is what the measurement actually is, how to read it, and why the quietness you experience depends as much on your own floor as on the pod.
Four questions that turn a number into a specification
If you read nothing else, read these. Any decibel claim that cannot answer all four is not comparable with any other decibel claim.
| Ask | Why it decides the number |
|---|---|
| Under which standard? | ISO 23351-1 is the standard written for enclosures of this kind. A figure with no named standard behind it has no defined method, which means no other figure can be compared with it. |
| Which quantity? | Speech level reduction answers "can people outside hear me talking?" Sound insulation quantities describe building elements and answer a different question. Both are printed in decibels and they are not interchangeable. |
| Which configuration? | Glazing area, door type and ventilation setting all move the result. The unit on the test report has to be the unit you are ordering, down to the options. |
| What is your background level? | A reduction is only meaningful relative to the noise already in the room outside. The same pod vanishes on a busy floor and is faintly audible in a quiet one. This is the variable no brochure can know. |
The fourth one is the one buyers never ask and the one that most often explains a disappointing pod. Everything else on this page is detail underneath these four.
What ISO 23351-1 actually measures
ISO 23351-1 is an international standard covering the measurement of speech level reduction for furniture ensembles and enclosures — which is to say, it was written for exactly this category of product rather than borrowed from building acoustics. Part 1 covers laboratory methods. It exists because the industry needed one defined way to answer a specific question, and before it there was none.
The question it answers
Not "how soundproof is this box" in the abstract, but something much narrower and more useful: when somebody speaks inside the enclosure, how much quieter is that speech outside it? A standardised speech source is placed in the pod, the sound outside is measured under controlled laboratory conditions, and the difference is the result. Because the source, the room and the method are all fixed by the standard, two pods tested this way can be compared directly.
It produces a single A-weighted figure
The result is one number in decibels, A-weighted — meaning it is filtered to approximate how human hearing responds across frequencies rather than treating all frequencies as equally audible. That is appropriate here, because the thing being judged is speech heard by a person. It also means the figure is already biased towards the frequencies that actually carry conversation, which is why a speech level reduction number is more useful to you than a raw broadband one.
It also sorts enclosures into classes
As well as the measured value, the standard groups enclosures into lettered performance classes. The class boundaries are defined in the standard itself, so ask a manufacturer to state both — the class and the measured value — and check them against the test report rather than the brochure. A class on its own hides where in the band a product sits; a value on its own leaves you doing the classification yourself.
What it does not tell you
It is a laboratory measurement of a product, not a prediction about your office. It says nothing about how loud the pod's own ventilation is, how much sound gets in from outside as opposed to out from inside, or what happens once the unit is assembled on a hard floor next to a glass partition. Those are real and they are covered further down — but none of them is a criticism of the standard, which is doing precisely the job it was written for.
Speech level reduction is not sound insulation
This is where most comparisons go wrong, and it is an easy mistake because both quantities are expressed in decibels and both get described in marketing copy as "dB reduction". They measure different things, under different standards, for different purposes. Putting one next to the other and picking the bigger number is not a comparison.
| Speech level reduction | Sound insulation | |
|---|---|---|
| Answers | Can people outside hear what I am saying? | How much sound energy does this construction stop? |
| Written for | Enclosures and furniture ensembles — products like pods | Walls, floors, doors and partitions — building elements |
| Weighting | A-weighted, biased towards speech frequencies | Assessed across a frequency range as a building element |
| Useful to you when | Judging privacy and whether a call will disturb the desks around it | Specifying a built meeting room or comparing partition systems |
Why a pod brochure might quote either
A manufacturer whose product performs well on one measure has every incentive to publish that one. Neither figure is dishonest in itself — the problem is a page that prints a number, calls it "dB reduction" and names no standard, leaving you to assume it is the same quantity as the pod you looked at yesterday. Ask which it is. It is a short question and the answer tells you a lot about who you are dealing with.
Privacy and quiet are also two different goals
Speech level reduction is about sound getting OUT — whether your conversation stays yours. Keeping open-plan noise OUT of the pod so you can concentrate is the reverse path, and while the two are related they are not the same measurement and a product can be better at one than the other. Decide which one you are buying for. A recruiter interviewing candidates cares most about the first; someone escaping the floor to do deep work cares most about the second.
What 25 dB, 30 dB and 35 dB do on a real floor
Decibels are logarithmic, which is why the gap between two figures matters more than it looks. The rule of thumb worth carrying is that a reduction of about 10 dB is perceived as roughly halving the loudness of a sound. So the step from 25 to 35 is not "forty per cent better" — it is closer to speech sounding half as loud again.
The number that actually decides it is not on the brochure
What a listener outside hears is the speech level after reduction, compared with the background noise already in that room. Once speech falls to around the background level it stops being intelligible; well below it, it stops being noticeable at all. That means the same phone booth dB reduction produces completely different outcomes in a busy open-plan floor and in a hushed one — and a quiet office is the harder case, not the easier one.
Roughly what each band buys you
Around 25 dB, a raised voice is still audible as voice on a quiet floor, though words are usually hard to make out once there is normal activity around the pod. Around 30 dB, speech typically drops to a murmur that blends into an ordinary working background. Around 35 dB and above, a normal speaking voice is effectively inaudible in most offices. Treat these as orientation rather than guarantees — which band you need is set by your floor, and the next paragraph is how to find out what your floor is.
Measure your own background before you shortlist
This takes ten minutes and no equipment beyond a phone. Use a sound level app at the position the pod will stand, at the busiest time of a normal day and again when the floor is quiet. You are not after laboratory accuracy — you are after the spread between the two. A floor with a high, steady background hides a lot and lets you buy lower down the range. A library-quiet floor, or one that empties in the afternoon, exposes everything and argues for the top of it.
Where the pod itself is the noise
One more figure worth asking for: how loud the pod is inside with the ventilation running and nothing else happening. A unit with excellent speech reduction and an intrusive fan is a bad place to take a call, and the ventilation noise also sets the floor below which outside noise cannot be heard anyway. People notice this within a week of installation and never from a specification sheet.
Why lab ratings differ from installed performance
A laboratory figure is a fair description of a product and a poor prediction of a room. The difference is not manufacturers overstating things — it is that the lab deliberately removes every variable your office supplies. Four of them matter.
Flanking paths
Sound travels around an enclosure as well as through it — along a hard floor, off a nearby glass partition, up into an open ceiling void. The lab controls these out. Your floor does not, and a pod placed in a hard, reflective corner will measurably underperform the same pod on carpet in open space.
Assembly and seal condition
The tested unit was assembled perfectly. Yours is built on site, and the acoustic result depends on the door pulling squarely onto a seal that compresses evenly. This is also the part that ages, which is why it leads our guide to what wears out in a used pod.
The door being open
Unglamorous and the largest effect on this list. A pod propped open because the ventilation feels stuffy, or because the door does not close cleanly on its own, delivers no reduction at all. Specification cannot fix a behaviour problem, but checking that the door self-closes properly can.
Your room, not the test room
The laboratory room has defined acoustic properties. A hard open-plan floor with glass and exposed services is more reverberant, so sound escaping the pod persists longer and travels further. The pod did not change; the room it is judged in did.
None of this makes the rating useless — it makes it a comparison tool rather than a promise. Use it to rank products against each other, then expect the installed result to sit somewhat below the laboratory one, and buy a margin rather than the exact figure you calculated you needed.
Checking a manufacturer's acoustic claim before you buy
Five questions, all of which a manufacturer who has done the testing can answer immediately. The informative part is often how quickly the answers arrive.
Ask for the test report, not the figure
A brochure number is a claim; a test report is evidence. It should name the testing laboratory, the standard and its version, the date, the quantity measured and the exact product configuration. You do not need to be able to read every page of it — you need it to exist, and to describe the pod you are being offered.
Check the tested configuration matches the quote
This is where otherwise honest numbers come unstuck. Glazing area, door construction, wall build-up and ventilation setting all affect the result, so a figure measured on the solid-walled version does not describe the fully glazed one you are specifying. Match the test report against the options on your quote line by line.
Confirm whether ventilation was running
A measurement taken with the fan off describes a pod nobody will ever sit in. Ask, and ask what the internal noise level is with ventilation at its normal setting. Together those two answers tell you more about what the unit will feel like than the headline reduction figure does.
Be wary of a bare number with no standard
"Up to 30 dB reduction" with nothing attached is not a specification and should not be weighed against a tested one. It may be perfectly accurate; there is simply no way to tell, and "up to" is doing a lot of work. Treat an unreferenced figure as marketing until somebody names the method behind it.
Ask to stand in one
Specifications rank products; your ears decide whether a product is right. Ten minutes inside a demonstration unit with someone talking normally outside tells you about ventilation noise, door feel and the actual experience of being in the box — none of which appears on any report. Where that is not practical, a refurbished unit of the same model is the cheapest way to find out before committing a fleet.
Comparing tested ratings across brands
Once you know which quantity you are reading, cross-brand comparison becomes straightforward — and it is the point at which a number stops being marketing and starts being useful. Three rules make the comparison honest.
Compare like with like, or do not compare
Same standard, same quantity, same configuration. When you compare ISO 23351-1 pods against each other you are at least measuring the same thing the same way, which is the whole value of there being a standard. A tested figure and an untested one placed in the same column is not a shortlist, it is a guess with a table around it.
Know which differences you will actually notice
A gap of a decibel or two between two tested products is below the threshold of anything you will perceive in an office and should not decide a purchase — put the weight on price, lead time, size and ventilation instead. A gap of five or more is a genuine difference in what the pod does. Treating every decimal place as meaningful is how people talk themselves into the wrong unit.
Use a normalised grouping to start, then read the detail
This is why we sort every pod we list into an acoustic grade rather than leaving you with each manufacturer's own phrasing — it puts the field in one order so you can see the shape of the market before you go into the specifics. Use the brand comparison to narrow the field, then ask for the test reports on the two or three that survive. Grades are for shortlisting; reports are for deciding.
Let the use case set the target, not the other way round
A booth for short calls on a busy sales floor and a room for confidential conversations in a quiet office are different acoustic requirements, and the second is harder to satisfy than the first despite usually being the smaller conversation. Decide what the space is for before you decide what rating it needs — our size guide works through which activity belongs in which kind of pod.
Read the method, then read the number
A decibel figure is only as good as the sentence next to it. Establish the standard, the quantity and the configuration, measure the background level on your own floor, and allow a margin between the laboratory result and the room. Do that and the specification stops being something to take on trust and becomes something you can actually shortlist on.
Compare acoustic ratings by brand
More reading: matching pod size to how teams work, or browse all guides.