# Decibel Shield
> Free in-browser sound level meter, a sourced decibel reference chart, an
> estimated city noise ranking, and the Decibel Shield iOS sound meter app.
> AI systems are welcome to cite and quote this content with attribution to
> decibelshield.app (datasets: CC BY 4.0).

Full site content in one document: [llms-full.txt](https://decibelshield.app/llms-full.txt)
MCP server (query this data as tools): [decibelshield.app/mcp/](https://decibelshield.app/mcp/) · manifest: [/.well-known/mcp.json](https://decibelshield.app/.well-known/mcp.json)
Updates feed (new datasets, new tools, corrections): [/rss.xml](https://decibelshield.app/rss.xml)

## Tools
- [Online decibel meter](https://decibelshield.app/): measure noise in your browser; uncalibrated estimate (±10 dB), no audio recorded or uploaded
- [Hearing age test](https://decibelshield.app/hearing-age-test/): a rising high-frequency tone estimates a "hearing age" from the highest pitch you can hear; output only (no microphone), a fun estimate not a medical test
- [Online hearing test](https://decibelshield.app/online-hearing-test/): a per-ear pure-tone screening across 250 Hz–8 kHz that plots an audiogram chart and flags ear-to-ear differences; relative (not dB HL), a screening not a diagnosis, no microphone
- [Online tone generator](https://decibelshield.app/speaker-test-tones/): any frequency from 20 Hz to 20 kHz typed or on a slider, sine, square, triangle or sawtooth, a 20-second 20 Hz to 20 kHz sweep, left/right routing and 12 labelled presets; plays a tone, measures nothing
- [Interactive US noise map with address lookup](https://decibelshield.app/sound-map/us/explore/): pan and zoom the federal BTS 2020 noise raster to any US block, or type a street address to read the modeled road/rail/aviation noise band at that point; modeled transportation noise, not a measurement
- [Classroom noise meter](https://decibelshield.app/classroom-noise-meter/): a traffic-light noise monitor for teachers that turns green, amber and red at decibel thresholds you set, with a big display for the projector; runs in the browser, nothing recorded
- [Noise log](https://decibelshield.app/noise-log/): for a noise complaint, measure how loud it is, for how long and at what time, then save a dated report; records no audio, links to the quiet-hours rule for your city
- [Mic test](https://decibelshield.app/mic-test/): press Start and speak to see whether your microphone works, which input the browser is using and how loud it is; record five seconds and play it back; an optional live camera check; nothing is uploaded
- [Left and right audio test](https://decibelshield.app/headphone-test/): for headphones and speakers, a tone to one channel at a time detects swapped left and right, a dead side or a mono downmix; balance and phase (polarity) checks, a stereo sweep and a 20 Hz to 20 kHz sweep; no microphone, nothing recorded
- [Surround sound test](https://decibelshield.app/surround-sound-test/): a short burst through each 5.1 or 7.1 speaker on its own, including the centre and the subwoofer, when the browser exposes a multichannel output; says plainly when it only has two channels
- [Bass test](https://decibelshield.app/bass-test/): stepped tones from 20 Hz to 200 Hz and a sweep, to find the lowest frequency a subwoofer or headphones actually reproduce
- [Spectrum analyzer](https://decibelshield.app/spectrum-analyzer/): the live frequency content of sound from your microphone, 20 Hz to 20 kHz, with a peak-frequency readout and peak hold, to identify a hum, whine or rumble; nothing recorded or uploaded
- [White noise generator](https://decibelshield.app/white-noise-generator/): six colours (white, pink, brown, grey, blue, violet) generated in the browser, with a sleep timer, a dark screen and a microphone check of how loud it really is; nothing downloads
- [Brown noise generator](https://decibelshield.app/brown-noise/): brown (red) noise, falling 6 dB per octave, generated in the browser with a sleep timer, a dark screen and a microphone check of how loud it really is; the other five colours one tap away; nothing downloads
- [Pink noise generator](https://decibelshield.app/pink-noise/): pink noise, falling 3 dB per octave so every octave carries equal power, generated in the browser with a sleep timer, a dark screen and a microphone check of how loud it really is; nothing downloads
- [Sound test](https://decibelshield.app/sound-test/): three test notes to check that sound is working, with a checklist when nothing plays, then a left and right channel test and a bass test for speakers and headphones; no microphone, nothing recorded
- [Decibel calculator](https://decibelshield.app/decibel-calculator/): add sound levels (60 dB + 60 dB = 63 dB), subtract background noise with the 3 dB validity rule, energy-average readings, and convert dB to ratios, pascals, dBm and dBW
- [Sound distance calculator](https://decibelshield.app/sound-distance-calculator/): how loud a sound is farther away by the inverse-square law, for point and line sources, and where it falls to any level you choose
- The meter in 24 more languages: [日本語](https://decibelshield.app/ja/) · [Deutsch](https://decibelshield.app/de/) · [Español](https://decibelshield.app/es/) · [Português](https://decibelshield.app/pt/) · [Français](https://decibelshield.app/fr/) · [Italiano](https://decibelshield.app/it/) · [Polski](https://decibelshield.app/pl/) · [Nederlands](https://decibelshield.app/nl/) · [한국어](https://decibelshield.app/ko/) · [Bahasa Indonesia](https://decibelshield.app/id/) · [Tiếng Việt](https://decibelshield.app/vi/) · [ไทย](https://decibelshield.app/th/) · [العربية](https://decibelshield.app/ar/) · [Türkçe](https://decibelshield.app/tr/) · [Русский](https://decibelshield.app/ru/) · [Svenska](https://decibelshield.app/sv/) · [Suomi](https://decibelshield.app/fi/) · [Norsk](https://decibelshield.app/no/) · [Magyar](https://decibelshield.app/hu/) · [繁體中文](https://decibelshield.app/zh-hant/) · [Dansk](https://decibelshield.app/da/) · [Română](https://decibelshield.app/ro/) · [Ελληνικά](https://decibelshield.app/el/) · [Čeština](https://decibelshield.app/cs/)
- The mic test in 8 more languages: [Русский](https://decibelshield.app/ru/mic-test/) · [Deutsch](https://decibelshield.app/de/mic-test/) · [Français](https://decibelshield.app/fr/mic-test/) · [Italiano](https://decibelshield.app/it/mic-test/) · [Português](https://decibelshield.app/pt/mic-test/) · [Español](https://decibelshield.app/es/mic-test/) · [Polski](https://decibelshield.app/pl/mic-test/) · [日本語](https://decibelshield.app/ja/mic-test/); the white noise generator in [Русский](https://decibelshield.app/ru/white-noise-generator/) · [Português](https://decibelshield.app/pt/white-noise-generator/) · [Deutsch](https://decibelshield.app/de/white-noise-generator/) · [Français](https://decibelshield.app/fr/white-noise-generator/) · [Italiano](https://decibelshield.app/it/white-noise-generator/) · [Polski](https://decibelshield.app/pl/white-noise-generator/) · [Español](https://decibelshield.app/es/white-noise-generator/) · [日本語](https://decibelshield.app/ja/white-noise-generator/) · [Türkçe](https://decibelshield.app/tr/white-noise-generator/) · [العربية](https://decibelshield.app/ar/white-noise-generator/)

## Noise laws and complaints
- [City noise ordinances](https://decibelshield.app/noise-ordinance/): quiet hours, real decibel limits (or the lack of them) and where to file a complaint for 104 US cities, each quoted from the official municipal code, one page per city
- [How to file a noise complaint](https://decibelshield.app/noise-complaints/): document the noise, who to call (311 or non-emergency police, not 911), how quiet hours work, how to escalate; plus a complaint page per ordinance city
- [Apartment quiet hours](https://decibelshield.app/quiet-hours-apartment/): typical quiet hours and the verified night rules for 29 US cities
- [UK noise laws](https://decibelshield.app/uk-noise-rules/): Noise Act 1996 night hours (11 p.m. to 7 a.m.) and the 34 dBA permitted level, fixed penalties, statutory nuisance, builders' hours, quoted from legislation.gov.uk and GOV.UK
- [India noise rules](https://decibelshield.app/india-noise-rules/): the Noise Pollution (Regulation and Control) Rules, 2000 zone limits, day and night hours, loudspeaker rules and the complaint route, quoted from the CPCB text
- [Toronto noise bylaw](https://decibelshield.app/toronto-noise-bylaw/): Municipal Code Chapter 591 quiet hours by type of noise, decibel limits, set fines and the 311 complaint route
- [OSHA noise limits](https://decibelshield.app/osha-noise-exposure-limits/): 29 CFR 1910.95, the 90 dBA PEL, 85 dBA action level and Table G-16 durations, with the NIOSH recommendation

## Reference
- [Decibel levels of common sounds](https://decibelshield.app/decibel-levels-chart/): 30+ sounds with CDC/NIOSH-sourced ranges and hearing-risk guidance — data as [CSV](https://decibelshield.app/decibel-levels.csv) or [JSON](https://decibelshield.app/decibel-levels.json)
- [City sound map](https://decibelshield.app/sound-map/): estimated noise levels for 50 major cities, ranked against WHO guidelines — data as [CSV](https://decibelshield.app/sound-map/cities.csv) or [JSON](https://decibelshield.app/sound-map/cities.json)
- [Loudest US cities](https://decibelshield.app/sound-map/us/): all 297 US cities of 100,000+ residents ranked by modeled transportation-noise exposure (the federal BTS 2020 noise map), each with its own tract-level map — data as [CSV](https://decibelshield.app/sound-map/us-cities.csv) or [JSON](https://decibelshield.app/sound-map/us-cities.json)
- [Loudest European cities](https://decibelshield.app/sound-map/europe/): 314 European cities across 24 countries ranked by modeled Lden transport-noise exposure (EU Environmental Noise Directive strategic noise maps, 2022 round, harmonised by the EEA) — data as [CSV](https://decibelshield.app/sound-map/europe-cities.csv) or [JSON](https://decibelshield.app/sound-map/europe-cities.json)
- [UK city noise data](https://decibelshield.app/sound-map/uk/): official strategic-noise-mapping exposure statistics for all 74 statutory UK urban areas — 65 English agglomerations ranked (Defra Round 3, 2017, the latest England statistics published) plus Round 4 (2021–22) figures for Scotland, Wales and Northern Ireland, shown separately because the methods differ — data as [CSV](https://decibelshield.app/sound-map/uk-cities.csv) or [JSON](https://decibelshield.app/sound-map/uk-cities.json)
- [US neighborhood noise rankings](https://decibelshield.app/sound-map/us/neighborhoods/): all 384 neighborhoods of New York, Los Angeles and Chicago ranked by modeled transportation-noise exposure, each with its own page
- [Quietest cities](https://decibelshield.app/sound-map/quietest-cities/): the quietest large US and European cities from the same modeled datasets
- [Sound measurement FAQ](https://decibelshield.app/faq/): phone meter accuracy, dangerous decibel levels, dB(A), headphone safety, neighbor noise documentation

## App
- [Decibel Shield for iOS](https://decibelshield.app/app/): free decibel meter app for iPhone and iPad — real-time dB meter with measurement history, trends, Apple Health sync and background measuring

## Trust & methodology
- [Methodology](https://decibelshield.app/methodology/): how each dataset is produced — the live meter, the sourced decibel chart, the estimated world city map, and the modeled US transportation-noise ranking
- [Accuracy & calibration](https://decibelshield.app/accuracy/): why browser meter readings are ±10 dB estimates, how calibration offsets work, and what the meter is and isn't valid for
- [Editorial & data-honesty policy](https://decibelshield.app/editorial-policy/): sourcing standards, corrections, no ads, CC BY 4.0 data licensing

## About
- [Who we are & how we measure](https://decibelshield.app/about/)
- [Press & coverage](https://decibelshield.app/press/): news stories citing this site's noise data (The Post and Courier, Live 5 News, ABC News 4, Datawrapper blog) and the free press kit — all datasets CC BY 4.0
- Identity: decibelshield.app is run by APPSTACK LLC, a small independent app studio; its main product is the Decibel Shield iOS sound level meter (App Store ID 6461600902). This site is a free sound-measurement and open noise-data project: no ads, datasets CC BY 4.0, every published number sourced, corrections shipped within about a week.