The short version
ISO 23351-2:2026 is a field method for measuring the apparent speech level reduction of office pods, booths and other enclosures after they are installed, in field conditions meeting engineering grade of accuracy. ISO published ISO 23351-2:2026 in August 2026. ISO 23351-1:2020, the laboratory method, remains the source of the class a pod is sold with. A field figure and a laboratory figure are different quantities.
Part 1 and Part 2 answer different questions, and a rating written for walls answers a third. Our explainer on ISO 23351-1, NIC and STC sets out what each was written to measure. This post covers the field method: what ISO published in August 2026, what the word apparent is doing in the quantity it reports, and what to ask a vendor who hands you a single number with no method attached. Where our own figures come from is stated plainly below, and it is a laboratory.
What ISO published in August 2026
ISO 23351-2:2026 carries a publication date of August 2026 and sits at stage 60.60, international standard published. The document is a first edition of 15 pages from technical committee ISO/TC 43/SC 2. Its title reads Acoustics, Measurement of speech level reduction of furniture ensembles and enclosures, Part 2: Field method.
ISO 23351-2:2026 applies to furniture ensembles and enclosures that one or more occupants can use. The exclusion in the abstract is narrower than it looks: ISO 23351-2:2026 rules out single components used in a workstation, naming a screen, a table and a ceiling absorber among them. A single desk screen is out of scope. A furniture ensemble is in scope, and so is an enclosure such as a 1-person phone booth. The distinction decides whether the method applies to one part of a workstation or only to the assembled thing a person sits inside.
How ISO 23351-2:2026 relates to the laboratory method in ISO 23351-1:2020
ISO 23351-1:2020 is a laboratory method for comparing products. Sound power is measured twice: once with a source in an empty room and no product present, and once with that source inside the product at the occupant's speaking position. The difference between those two levels, in 1/1-octave bands from 125 Hz to 8000 Hz, is the level reduction. Speech level reduction expresses that difference as a reduction in A-weighted sound power of standard speech. The full text is ISO 23351-1:2020, paywalled at iso.org.
Direction is built into that setup. The source sits where an occupant's mouth would be, so ISO 23351-1:2020 describes speech leaving the enclosure, not sound travelling into it. A vendor who promises the occupant will not hear the office is describing something the test did not measure.
| Question | ISO 23351-1:2020 | ISO 23351-2:2026 |
|---|---|---|
| Where the test happens | Laboratory: the source in an empty room, then inside the product at the occupant position | The building the product was installed in |
| Quantity reported | Speech level reduction | Apparent speech level reduction |
| The surrounding room | Kept out by the laboratory setup | Part of the result, which is why it is apparent |
| What the result is good for | Comparing one product against another | Measuring one installation as it was built |
Keranen, Hakala and Hongisto compared ASTM E596-96 with ISO 23351-1 across four phone booths and concluded the ISO method is "more suitable for assessing the acoustic properties of phone booths" where speech is the main sound source, because its single number describes the reduction of A-weighted speech the product produces. ASTM E596-96 gives more generic enclosure data with no limitation on the sound source. See Comparison of ASTM E596-96 and ISO 23351-1 methods for sound reduction measurements of working booths, Forum Acusticum 2023, pages 3673 to 3677.
Why ISO 23351-2:2026 measures apparent speech level reduction
One word in that quantity does most of the work, and almost nobody explains it. In a laboratory the test object is isolated, so the number belongs to the object. In a building nothing is isolated. Room reverberation, the paths sound takes around an enclosure rather than through it, and the background noise during the measurement all land in the result. ISO 23351-2:2026 therefore reports the apparent performance of the object as installed, in that room, on that floor, under that ceiling.
Building acoustics has used the convention for decades. Airborne sound insulation is written as R in the laboratory and as R' in the field, the prime showing that flanking transmission through the surrounding structure is part of the figure. Apparent works the same way. An Arc S Pod at $6,495 in a carpeted corner and the same model under a hard ceiling on an open floor are two measurements of one product, and two different apparent values are the method working, not failing.
Laboratory and field
The same pod, two methods, two different quantities
In the laboratory panel, a source on a bare floor line sends out four full wavefronts, and the same source inside the pod leaves only two short faint ones. In the field panel, that same pod stands in an occupied room with a ceiling, a floor and a desk nearby, where sound reflects off the ceiling, travels over the pod rather than through it, and background noise arrives from outside the room.
Laboratory
ISO 23351-1:2020
The room is kept out of the answer.
- 1The source alone in an empty room, with no product present
- 2The same source inside the pod, at mouth height
Reported as speech level reduction, a property of the product.
Field
ISO 23351-2:2026
The room is part of the answer.
- 1Reverberation off the room surfaces
- 2Paths around the pod, not through it
- 3Background noise during the measurement
Reported as apparent speech level reduction, a property of this installation.
What engineering grade of accuracy means when you specify a pod
The abstract of ISO 23351-2:2026 states that the method determines apparent speech level reduction in field conditions meeting engineering grade of accuracy. Read it closely: the grade and the conditions are stated together. ISO set the accuracy expectation inside the standard rather than leaving it to whoever quotes the result, and the conditions live in the 15-page text, not a sales sheet.
Before August 2026 the ISO 23351 series had no field part. ISO 23351-2:2026 adds a second instrument alongside the laboratory classification: performance can be measured in the building the pod was installed in, under a published international method, and handed to an acoustician or a landlord without an argument about how it was obtained. A Part 2 figure is still not a laboratory classification, and presenting one as the other claims something the standard does not support. Check editions too: ISO 3382-3:2022 is the current open-plan office room acoustics standard, and the 2012 edition was withdrawn on 3 January 2022.
- Which part of ISO 23351 produced this figure, ISO 23351-1:2020 in the laboratory or ISO 23351-2:2026 in the field?
- For a field result, which room, and what was the background noise at the time?
- Which direction was measured, speech leaving the enclosure or sound entering it?
Where PrivacyPod sits on ISO 23351
The enclosed PrivacyPod pods are ISO 23351-1 Class A certified, with approximately 30 dB of speech level reduction, measured under the laboratory method in ISO 23351-1:2020. Class A is the top band. That figure describes speech leaving the pod and reaching the room, and we publish no figure for sound travelling the other way. PrivacyPod has not published a field measurement under ISO 23351-2:2026, and no figure on this site is presented as one. When a Part 2 result exists for our office pods, it will be named as one, with the room and the conditions stated.
The claim applies to the enclosed pods across the range, including the 1-person S Pod at $6,395, the S Pod Plus at $6,995 and the curved Arc S Pod at $6,495. Footprints sit side by side on the pod comparison page, and the full certification list covers UL Listed, GREENGUARD Gold Certified and the ISO management standards.
Questions about ISO 23351-2:2026
Does ISO 23351-2:2026 replace ISO 23351-1:2020?
No. ISO 23351-1:2020 remains the laboratory method for comparing products, and ISO 23351-2:2026 adds a field method for measuring one installation in place. Both are current.
Can an office pod be classified under ISO 23351-2:2026?
The class a pod is sold with comes from the laboratory method in ISO 23351-1:2020. The enclosed PrivacyPod pods are ISO 23351-1 Class A certified, measured under that method. Anyone quoting a class should say which part and which edition produced it.
Why will a field measurement differ from the laboratory figure?
ISO 23351-2:2026 reports apparent speech level reduction, and apparent means the surrounding room is part of the answer. Reverberation, flanking paths and background noise all contribute in a building and are kept out of a laboratory. Expect a difference.
Is ASTM E596 withdrawn now that ISO 23351-2:2026 exists?
No. ASTM E596-22 is active, last updated on 31 October 2022. It places the sound source outside the enclosure, and its result may be used to rank enclosures by noise isolation class, NIC. The standard itself cautions against reading that figure as how well an enclosure holds in a source placed inside it. See what NIC and STC were written to measure.
How long does a certified pod take to arrive?
Quick-Ship models ship in 1 to 2 weeks and made-to-order builds take 9 to 11 weeks. Shipping is free on every order, and every pod carries a 3-year limited warranty. Finishes change availability, so ask for a lead time on your configuration.
Does PrivacyPod publish an ISO 23351-2 field measurement?
Not today. The published claim for the enclosed PrivacyPod pods is ISO 23351-1 Class A certified, approximately 30 dB of speech level reduction, from the laboratory method in ISO 23351-1:2020. If a project needs an in-situ measurement under Part 2, talk to the team before the specification is written.
Filed under Acoustics & certification
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