Noise occupies a strange place in the office ledger: it is the environmental complaint employees rank above temperature, air quality and even ergonomics, yet it is also the fit-out item most often treated as decoration — a felt hexagon above the meeting booth, chosen for its colour. The acoustic literature is unusually quantitative about what this costs, because open-plan speech privacy can be measured, modelled and, when it fails, converted into lost working hours. This piece does that conversion, then ranks the fixes by euro per decibel.
What open-plan offices measure — and what the standards ask for
The measured reality first. In one of the most thorough field studies available — a study of real occupants in their actual workstations, reported in the Journal of the Acoustical Society of America — open-plan office noise measured on average 53.9 dB(A) (4-hour LAeq, range 48.3–58.5) at workstations. Guidance comfort zones ask for something quieter: ISO 3382-3’s evaluation annex treats a background noise level of roughly 40–45 dB(A) as good conditions, while the related comfort-distance definition uses 45 dB(A) of residual speech as the threshold for being left alone. The typical office therefore sits 8 a 14 decibels above the level its own standard calls comfortable — and a decibel is a doubling of sound energy, so “a little louder” understates the gap.
STI and ISO 3382-3: the speech-privacy numbers
Total decibels are only half the story, because the distractor in an office is not a hum — it is someone’s sentence. ISO 3382-3, the standard for measuring open-plan office acoustics, quantifies this with metrics built on the Speech Transmission Index (STI), which scores how intelligently a voice arrives at a listener’s ear:
- D₂,S — spatial decay of speech: how fast speech level dies away. Good: > 8 dB. Typical measured offices: < 5 dB.
- Lp,A,S,4m — speech level 4 metres away: good ≤ 48 dB(A); most offices exceed 52 dB(A).
- rD — distraction distance (where STI falls below 0.5, i.e. you can still follow the conversation): good < 5 m; measured offices commonly 10–11+ m. Peer-reviewed modelling in PLOS One confirms that most open-plan offices fall on the poor side of every one of these metrics.
Translation for the floor plan: in a typical open-plan office, anyone within three or four desks of you can understand you, and you them, all day. That is the mechanism behind every number in the next section.
The productivity cost in published numbers
The peer-reviewed chain of evidence is short but direct. A field study published in PMC (Hansen et al.) measured cognitive performance in activity-based workplaces: employees in open-plan areas performed Informazioni 14% worse on serial-memory tasks than those in cell offices with ~15 dB lower noise; moving a worker from a noisy active zone to a quiet zone raised measured performance by 16.9%, and to an individual room by 21.9%. Following Jahncke’s work on speech distraction (8–10% performance decrements on memory and information-search tasks), the authors’ own order-of-magnitude costing puts a 14% decrement at roughly USD 6,700 per employee per year at average US wages. Rockwool’s “Boosting Business with Better Acoustics” report aggregates the broader literature: open-plan offices without noise mitigation reduce productivity by up to 15%, the average employee loses 21.5 minutes of concentrated work per day, and citing a BPIE estimate, each decibel of reduction is worth ~0.3% of productivity — taking an office from 55 a 45 dB(A) saves over €1,800 per employee per year in its costing. Treat these as the sourced ranges they are, not as guarantees; but note that even the conservative floor — the €1,800 figure — dwarfs every intervention cost below by an order of magnitude per head.
The behavioural evidence confirms the money is real: in the JASA field study, when disturbed at their workstation, 55% of occupants put on headphones, 40% took a break, e 33.5% physically relocated — that is the productivity loss happening visibly, one escape at a time.
Fixes ranked by cost per effect
We rank interventions by measured acoustic effect against published prices, cheapest first. Published prices from US vendors are converted at ~€0.92 per dollar.
| Intervention | Published cost | Measured / standardised effect | Honest caveat |
|---|---|---|---|
| Move concentrative work to quiet rooms / library rules | ≈ €0 if rooms exist | +16.9% a +21.9% measured cognitive performance (PMC field study) | Needs enough quiet capacity or it becomes a booking war |
| Rearrange desks: greater spacing, no face-to-face pairs | ≈ €0 (labour) | Best speech privacy at existing partition height (Peer-reviewed ISO 3382-3 field experiment) | Fights org charts and managers who want to be seen |
| Carpet, curtains, soft partitions, ceiling baffles/clouds | €700–1,500 per 8-desk zone (ceiling clouds); panels €260–1,100 | Cuts reverberation; raised porous 1.3 m screens cut speech-at-4 m below 48–49 dB in EURAC measurements | Absorption ≠ privacy: kills echo but speech still carries |
| Higher, porous desk partitions (≥1.3 m, damped) | Fit-out pricing, varies | Speech at 4 m: 50.8 dB (no screens) → 48.3 dB (porous) — moves but doesn’t reach ISO “good” 48 dB alone | Face-to-face layouts still leak; height alone insufficient |
| Sound masking (commissioned) | ≈ €16–28/m² installed (€1.50–3.00/ft²); 465 m² system ≈ €30/m² (Soft dB) | Directly engineered to raise rD/rP toward ISO 3382-3 good values | Only works commissioned (€1,400–3,700); some occupants dislike it — pilot a zone |
| Personal active-noise-cancelling headphones | €100–350 each, often expensed | Covers personal mitigation used by the 55% already wearing headphones | Removes collaboration, not just noise; treat symptom, not cause |
The ranking’s uncomfortable headline: the two highest-effect interventions on the table cost almost nothing, and both are management decisions — quiet rooms and desk geometry — while the purchase-ordered solutions (panels, masking) sit behind them. That is why sound money keeps getting spent on felt.
What this means for your office
Measure before you buy, and measure the right thing: a sound-level meter reading 54 dB(A) at your desks tells you you’re ~9 dB over comfort, and a simple STI-based walk-through (or a hired ISO 3382-3 measurement, typically the €1,000–4,600 acoustic-assessment line item) tells you how far your distraction distance runs. Then sequence: designate and staff quiet rooms first (free, largest measured effect); re-lay desks for spacing and sight-lines; add absorption where voices are loudest; commission masking only for the zones that still fail the numbers. Against a sourced cost of distraction in the low thousands of euros per employee per year, a four-figure acoustic budget is not a fit-out nicety — it is the cheapest productivity on the market.
Fonti
- Journal of the Acoustical Society of America — Noise disturbance and lack of privacy: modeling acoustic dissatisfaction in open-plan offices (measured 53.9 dB(A); coping behaviours)
- ODEON application note — ISO 3382-3 metrics and good/poor target values
- PLOS One — Influence of partition layouts on speech privacy in open-plan offices (ISO 3382-3 field experiment)
- PMC (Hansen et al.) — Objective cognitive performance in activity-based workplaces (14% open-plan deficit; 16.9%/21.9% quiet-room gains; cost estimate)
- ROCKWOOL — Boosting Business with Better Acoustics (BPIE 0.3%/dB estimate; €1,800/employee/yr)
- Forum Acusticum 2025 — Desk partition designs and material choices (speech-at-4 m measurements)
- Soft dB — Sound masking cost per m²
- TSS — Sound masking installed pricing ($1.50–3.00/ft², commissioning)
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