Last updated: 27 September 2026
In short: These are the primary sources behind the numbers on SoundDBMeter.com: workplace noise law, public-health guidance, measurement standards and loudness standards. Each entry says what we use it for and which of our pages rely on it.
References support education; they do not turn a browser into a calibrated instrument. Browser readings remain estimates, as explained in how accurate an online decibel meter is. SoundDBMeter.com is not affiliated with any organisation listed here, and listing a source does not mean it endorses the site or its tools. How we choose sources is set out in the editorial policy.
Workplace noise limits
OSHA 29 CFR 1910.95: Occupational noise exposure
The US legal limit: 90 dB(A) over 8 hours with a 5 dB exchange rate, the 85 dB(A) action level for a hearing conservation programme, and no continuous exposure above 115 dB(A).
Used on: OSHA and NIOSH exposure time limits, noise exposure calculator
NIOSH: Criteria for a Recommended Standard, Occupational Noise Exposure (1998, publication 98-126)
The recommended limit of 85 dB(A) over 8 hours with a 3 dB exchange rate. It is the basis of the safe listening times we show beside readings and levels.
Used on: sound decibel meter (safe time at 80 dB(A) and above), is 85 dB dangerous? and the other level pages
EU Directive 2003/10/EC: noise at work
The European lower and upper action values of 80 and 85 dB(A) and the 87 dB(A) exposure limit value, for readers in Europe.
Used on: how loud is a concert, how loud is a gunshot
Hearing health and safe listening
WHO’s safe-listening work, including the WHO-ITU standard for personal audio devices (80 dB for 40 hours a week for adults, 75 dB for children).
Used on: how loud are my headphones, safe headphone volume for kids
Community and environmental noise
WHO: Guidelines for Community Noise (1999)
Night-time and bedroom targets, such as 30 dB(A) for continuous noise in a bedroom, used as the sleep target in our background noise test.
Used on: bedroom noise level for sleep, background noise test
WHO: Environmental Noise Guidelines for the European Region (2018)
Recommended limits for road, rail, aircraft, wind turbine and leisure noise.
Used on: how loud is a jet engine
The 70 dB 24-hour average identified to protect hearing, and the 55 and 45 dB day-night levels for outdoor and indoor residential areas.
Used on: safe noise levels chart
Measurement standards
IEC 61672-1: Sound level meters, specifications
The A- and C-weighting curves and the Fast (125 ms) and Slow (1 s) time weightings. Our meter’s weighting filters are tested against its table. The US counterpart, ANSI/ASA S1.4, covers the same ground.
Used on: dB vs dBA, dBA vs dBC
ANSI/ASA S12.60: Acoustical performance criteria for schools
The 35 dB(A) background level for unoccupied classrooms, used with WHO guidance for the classroom target.
Used on: classroom noise level and monitor
ISO 1996-1: Description, measurement and assessment of environmental noise
Standard definitions of the equivalent continuous level (Leq) and percentile levels such as L10 and L90, which our noise monitor and background noise test report.
Used on: what is Leq
Audio loudness
EBU R 128: Loudness normalisation and permitted maximum level
The −23 LUFS broadcast target, loudness range and true-peak limit. The loudness meter’s engine is tested with the EBU Tech 3341 and 3342 test cases.
Used on: audio loudness meter
ITU-R BS.1770: Algorithms to measure audio programme loudness and true-peak level
K-weighting, gating and true-peak measurement. The loudness meter’s K-weighting matches the published coefficients.
Used on: the same audio loudness meter (LUFS and true peak)
Browser technology
Our microphone tools are built on the W3C Web Audio API and the Media Capture API (getUserMedia), which let a page read the microphone only after you allow it and process the audio on your device. How the pieces fit together is explained on how it works, and you can check your own input with the microphone test.
Our own tests
Some statements come from our own tool tests rather than an outside source, for example how closely the meter’s A-weighting follows the IEC table. Those results, and what was not tested, are on the testing methodology page. To bring a browser reading closer to a real level, see how to calibrate your microphone.
Updates and broken links
Standards and guidance are revised from time to time. We check these references when a page is updated and replace a link if a source moves. If you find an outdated source, a broken link or a claim that does not match its source, please tell us through the contact page.