Every company has conversations that must not reach a third pair of ears: salary negotiations, health matters, ending an employment relationship, client personal data. An open floor has no place for them — in practice they happen in the stairwell or the park.
What “inaudible” has to mean
There is an important distinction that often gets lost. An enclosure can attenuate sound so the conversation seems quiet — that is not the same as inaudible. If the words can be made out, the conversation is not confidential.
This is precisely what ISO 23351-1 was written to quantify. It rates speech level reduction: how far the level of a voice raised inside the enclosure has dropped by the time it is measured outside. It is the one figure that maps directly onto the question a compliance officer is actually asking — not “how quiet is it” but “can the words be recovered”. Where a supplier can quote a class under that standard, the answer is documented rather than asserted.
Privacy is not only courtesy
If an employee's personal data is audible at the next desk, that is not merely awkward. GDPR obliges the employer to apply appropriate technical and organisational measures to protect personal data — and a space where the conversation can be overheard does not meet that condition.
The same holds for client data. A sales call naming a client's turnover or contract terms is confidential information even when nobody is deliberately listening.
The number that decides it
Certified 35 dB insulation means a normal conversation can no longer be distinguished one metre from the enclosure. At around 25 dB you hear that someone is speaking but not what. For confidential conversations that difference decides: choose Solo, or Duet for conversations held by two, rather than the Lite range.
Which conversations need a separate space
A practical list: salary and review conversations, health matters and sick leave, ending employment, recruitment interviews, client financials and contract terms, internal investigations.
What the data protection officer will ask
When this goes past a DPO rather than an office manager, the questions change shape. Is the attenuation certified by an independent laboratory, and under which standard. Is the door seal part of the tested configuration, since the seal carries the result. Can the space be seen into as well as heard — a glass front with a screen visible from the corridor defeats the purpose for anything involving records on screen. And is the measure documented, because an appropriate technical measure that exists only in practice is difficult to evidence in an audit.
None of these are difficult to satisfy; they are simply easier to satisfy before purchase than after. Test reports and certificates for the range are published by the manufacturer.
Two common misconceptions
“We will keep our voices down.” Whispering lowers the volume, but whispered speech is often more intelligible against background noise than normal speech.
“Let us go to the coffee corner.” A coffee corner is an open space that simply has no desks. Audibility is the same, often better because of the hard surfaces.
In one sentence
If the content of a conversation must not travel, a quiet corner is not enough — you need measured and certified insulation. For rooms shared by four, see Quartet.