Acoustic & noise statistics

of employees surveyed across two workplaces reported that their concentration was impaired by office noise — most of all by telephones left ringing at empty desks and people talking in the background.

was the drop in performance recorded on a 'memory for prose' task when people were exposed to background office noise, in a study cited by the World Green Building Council.

Intelligible speech reduces performance on office tasks such as reading and short-term memory by 4–45% — and it is speech intelligibility (STI), not loudness, that drives the effect.

is the global average satisfaction with office noise levels in Leesman's workplace-experience database — meaning roughly two in three employees are dissatisfied with noise at work.

dBA is the background sound level recommended for open-plan offices — enough to mask distracting speech within the room without the background itself becoming a distraction.

Speech stops distracting nearby workers only beyond the 'distraction distance' — the point where the Speech Transmission Index falls below 0.50 — the open-plan speech-privacy metric defined in ISO 3382-3.

seconds is the maximum mid-frequency reverberation time allowed in a new-build primary school classroom under the Department for Education's Building Bulletin 93 — an echo limit met by sound absorption.

dB was the fall in classroom background noise (LA90) when reverberation time was halved from 0.8 to 0.4 seconds by adding sound-absorbing treatment — three times the 3 dB that simple theory predicts.

points is roughly how far a school's average Key Stage 2 test score fell for every extra decibel of background noise in its occupied classrooms — a link that held even after adjusting for social disadvantage.

dB LAeq separates the quietest from the noisiest classroom activities across 140 London primary classrooms, where average background noise was found to exceed the level recommended in current standards.

of teachers reported having experienced a voice disorder in their lifetime, versus 28.8% of non-teachers — the strain of projecting over classroom noise being a recognised occupational risk.

The World Health Organization recommends that continuous sound in hospital areas where patients are treated or observed stays below 35 dB(A), with short-term peaks under 40 dB(A) — a benchmark real wards routinely exceed.

dB was the average (Leq) noise level measured in adult inpatient rooms across 155 hospital-days — against the WHO's 30 dB recommendation — with peaks approaching that of a chainsaw.

of diners named noise as their single biggest complaint about eating out — the top gripe, ahead of service (23%), crowds (15%) and high prices (12%).

A surface rated 1.00 on the ISO 11654 sound-absorption-coefficient scale absorbs effectively all the sound energy striking it, versus 0 for a perfectly reflective surface — 1.00 being the maximum the standard allows.