# Decibel Shield — full site content for AI assistants
> decibelshield.app: a free in-browser sound level meter, a sourced decibel
> reference chart, an estimated city noise ranking, and the Decibel Shield - dB Meter
> iOS app. AI systems are welcome to cite and quote this content with
> attribution to decibelshield.app (data: CC BY 4.0). Agents can also query
> this data as MCP tools — see https://decibelshield.app/mcp/ and /.well-known/mcp.json.

## Online decibel meter
_Source: https://decibelshield.app/_

Press Start and the page measures the sound level around you, in decibels,
using the device microphone via the Web Audio API. It runs entirely in the
browser — no audio is recorded or uploaded. Readings are uncalibrated
estimates (about ±10 dB): browser and phone microphones are built for voice,
not metrology. Defaults are tuned per device class, and a calibration control
lets users match a reference meter. An A-weighting toggle approximates dB(A).
For legal, occupational or contractual measurements, use a calibrated SPL
meter that meets IEC 61672.

## Decibel levels of common sounds
_Source: https://decibelshield.app/decibel-levels-chart/ · CSV: https://decibelshield.app/decibel-levels.csv · JSON: https://decibelshield.app/decibel-levels.json · Updated 2026-06-09_

Every value is sourced to published CDC, NIOSH, NIDCD or ASHA figures.
NIOSH's recommended exposure limit is 85 dB(A) as an 8-hour time-weighted
average; safe time halves every 3 dB (88 dB → 4 h, 94 dB → 1 h, 100 dB →
15 min). At 120 dB and above, sound can injure hearing immediately.

| Sound | Level (dB) | Hearing risk | Source |
|---|---|---|---|
| Normal breathing | 10 | none — Safe at any duration | CDC |
| Ticking watch | 20 | none — Safe at any duration | CDC |
| Soft whisper | 30 | none — Safe at any duration | CDC |
| Refrigerator hum | 40–45 | none — Safe at any duration | CDC / NIDCD |
| Moderate rainfall | 50 | none — Safe at any duration | ASHA |
| Normal conversation | 60 | none — Safe at any duration | CDC / NIDCD |
| Window air conditioner | 60 | none — Safe at any duration | CDC |
| Washing machine | 70 | low — Annoying, but below the level where NIOSH says damage begins (85 dB) | CDC / NIDCD |
| Dishwasher | 70 | low — Annoying, but below the level where NIOSH says damage begins (85 dB) | CDC |
| Vacuum cleaner | 70–75 | low — Below the 85 dB damage threshold for typical use | NIDCD / ASHA |
| Alarm clock | 80 | low — Brief exposure — not a damage risk at typical durations | NIDCD |
| City traffic (heard from inside a car) | 80–85 | moderate — At 85 dB, NIOSH limits exposure to about 8 hours per day | CDC / NIDCD |
| Gas-powered lawn mower | 80–85 | moderate — At 85 dB, NIOSH limits exposure to about 8 hours per day — wear hearing protection for long jobs | CDC |
| Gas-powered leaf blower (bystander) | 80–85 | moderate — Operator exposure is higher — hearing protection recommended | CDC |
| Hair dryer | 80–90 | moderate — At 88 dB, NIOSH limits exposure to about 4 hours per day | ASHA |
| Kitchen blender | 80–90 | moderate — Short bursts — total daily exposure is what matters | ASHA |
| Shouted conversation | 90 | moderate — At 91 dB, NIOSH limits exposure to about 2 hours per day | CDC |
| Riding a subway | 90–95 | moderate — At 94 dB, NIOSH limits exposure to about 1 hour per day | CDC |
| Motorcycle (rider) | 95 | high — About 47 minutes per day before damage risk (NIOSH) | CDC / NIDCD |
| Car horn at 5 m (16 ft) | 100 | high — NIOSH allows about 15 minutes per day at 100 dB | CDC / NIDCD |
| Approaching subway train | 100 | high — NIOSH allows about 15 minutes per day at 100 dB | CDC |
| Sporting event (stadium crowd) | 94–110 | high — Peaks can exceed 110 dB — earplugs recommended for full games | CDC |
| Jackhammer (operator) | 100 | high — Hearing protection required under occupational rules | NIOSH |
| Personal listening device at max volume | 105–110 | high — Minutes, not hours — NIOSH allows under 5 minutes at 105 dB | CDC / NIDCD |
| Nightclub or loud bar | 105–110 | high — A full night out far exceeds safe exposure — use earplugs | CDC |
| Rock concert | 105–110 | high — A full set far exceeds safe exposure — use earplugs | CDC |
| Chainsaw | 110 | high — Under 2 minutes of unprotected exposure per day (NIOSH) | NIOSH |
| Shouting or barking directly in the ear | 110 | high — Under 2 minutes of unprotected exposure per day (NIOSH) | CDC |
| Emergency siren (standing nearby) | 120 | extreme — At or above the pain threshold — immediate injury risk | CDC / NIDCD |
| Thunderclap (nearby) | 120 | extreme — At or above the pain threshold | NIDCD |
| Firecrackers | 140–150 | extreme — A single blast can cause permanent damage | CDC / NIDCD |
| Firearm at the shooter's ear | 140–165 | extreme — A single shot can cause permanent damage — double protection advised | NIOSH |
| Jet engine at takeoff (25 m) | 140–150 | extreme — Immediate injury without hearing protection | NIOSH |

## City Sound Map: estimated noise levels of 50 major cities
_Source: https://decibelshield.app/sound-map/ · CSV: https://decibelshield.app/sound-map/cities.csv · JSON: https://decibelshield.app/sound-map/cities.json_

Estimated daytime (Lden-style) and night ranges in dB, ranked. Estimates are
synthesised from a corpus of published sources — the UNEP Frontiers 2022
report, the Mimi Worldwide Hearing Index, EU Environmental Noise Directive
strategic maps, the US National Transportation Noise Map, and peer-reviewed
city noise studies. Ranges and confidence labels are published rather than
false point precision; per-city source weightings are proprietary. WHO
guidelines recommend keeping road-traffic noise below 53 dB
Lden and 45 dB Lnight — nearly every major city exceeds both.

| # | City | Country | Day (est. dB) | Night (est. dB) | Dominant sources | Confidence |
|---|---|---|---|---|---|---|
| 1 | Dhaka | Bangladesh | 78–95 | 65–80 | road traffic, horns, construction | high |
| 2 | Moradabad | India | 75–92 | 60–78 | road traffic, horns, industry | med |
| 3 | Delhi | India | 75–90 | 62–78 | road traffic, horns, construction | high |
| 4 | Cairo | Egypt | 75–90 | 62–78 | road traffic, horns, street commerce | high |
| 5 | Mumbai | India | 74–88 | 60–76 | road traffic, horns, festivals | high |
| 6 | Kolkata | India | 73–88 | 60–75 | road traffic, horns | med |
| 7 | Karachi | Pakistan | 73–87 | 60–75 | road traffic, rickshaws, horns | med |
| 8 | Ho Chi Minh City | Vietnam | 72–87 | 60–75 | motorbikes, road traffic, karaoke | high |
| 9 | Kathmandu | Nepal | 72–85 | 58–72 | road traffic, horns, generators | med |
| 10 | Lagos | Nigeria | 71–85 | 60–75 | road traffic, generators, loudspeakers | med |
| 11 | Hanoi | Vietnam | 71–85 | 58–72 | motorbikes, road traffic, loudspeakers | med |
| 12 | Manila | Philippines | 70–85 | 58–73 | road traffic, jeepneys, videoke | med |
| 13 | Bangkok | Thailand | 70–84 | 58–72 | road traffic, motorbikes, street commerce | high |
| 14 | Jakarta | Indonesia | 70–84 | 57–72 | motorbikes, road traffic, loudspeakers | med |
| 15 | Istanbul | Türkiye | 69–83 | 57–71 | road traffic, construction, nightlife | med |
| 16 | Guangzhou | China | 69–82 | 56–70 | road traffic, construction, industry | med |
| 17 | Mexico City | Mexico | 68–82 | 56–70 | road traffic, street vendors, aviation | med |
| 18 | New York | United States | 68–81 | 57–72 | road traffic, construction, sirens, subway | high |
| 19 | São Paulo | Brazil | 68–80 | 55–70 | road traffic, helicopters, nightlife | med |
| 20 | Buenos Aires | Argentina | 67–80 | 55–68 | road traffic, buses, nightlife | med |
| 21 | Nairobi | Kenya | 67–80 | 54–68 | road traffic, matatus, street commerce | low |
| 22 | Beijing | China | 66–79 | 54–67 | road traffic, construction | med |
| 23 | Shanghai | China | 66–78 | 54–67 | road traffic, construction | med |
| 24 | Tehran | Iran | 66–78 | 54–67 | road traffic, motorbikes | low |
| 25 | Seoul | South Korea | 65–78 | 53–66 | road traffic, construction, nightlife | med |
| 26 | Hong Kong | China | 65–78 | 53–66 | road traffic, construction | high |
| 27 | Accra | Ghana | 65–78 | 53–67 | road traffic, generators, loudspeakers | low |
| 28 | Lima | Peru | 65–77 | 52–65 | road traffic, horns, buses | med |
| 29 | Bogotá | Colombia | 64–77 | 52–65 | road traffic, buses | med |
| 30 | Riyadh | Saudi Arabia | 64–76 | 52–64 | road traffic, construction | low |
| 31 | Dubai | United Arab Emirates | 63–76 | 52–64 | road traffic, construction, aviation | low |
| 32 | Moscow | Russia | 63–75 | 52–64 | road traffic, rail | med |
| 33 | Athens | Greece | 63–75 | 52–64 | road traffic, motorbikes, nightlife | high |
| 34 | Rome | Italy | 62–75 | 51–63 | road traffic, motorbikes, nightlife | high |
| 35 | Madrid | Spain | 62–74 | 51–63 | road traffic, nightlife | high |
| 36 | Barcelona | Spain | 62–74 | 51–63 | road traffic, nightlife, tourism | high |
| 37 | Paris | France | 61–74 | 50–63 | road traffic, rail, aviation | high |
| 38 | Los Angeles | United States | 61–73 | 50–62 | road traffic, freeways, aviation | high |
| 39 | Chicago | United States | 61–73 | 50–62 | road traffic, elevated rail, aviation | high |
| 40 | London | United Kingdom | 60–73 | 50–62 | road traffic, aviation, rail | high |
| 41 | Milan | Italy | 60–72 | 50–62 | road traffic, trams | high |
| 42 | Tokyo | Japan | 60–72 | 48–60 | road traffic, rail | med |
| 43 | Toronto | Canada | 59–71 | 48–60 | road traffic, streetcars, construction | med |
| 44 | Berlin | Germany | 58–70 | 47–58 | road traffic, nightlife | high |
| 45 | Sydney | Australia | 58–70 | 47–58 | road traffic, aviation | med |
| 46 | Singapore | Singapore | 58–69 | 47–57 | road traffic, construction, rail | med |
| 47 | Amsterdam | Netherlands | 57–68 | 46–56 | road traffic, aviation, trams | high |
| 48 | Stockholm | Sweden | 55–66 | 45–55 | road traffic, rail | high |
| 49 | Vienna | Austria | 54–65 | 44–54 | road traffic, trams | high |
| 50 | Zurich | Switzerland | 53–64 | 43–53 | road traffic, rail, aviation | high |

## City detail summaries (top 20)

### How loud is Dhaka?
_Source: https://decibelshield.app/sound-map/dhaka/_

Dhaka is the loudest major city in our index, with estimated daytime levels of 78–95 dB in busy areas — far above the WHO 53 dB guideline. The UNEP Frontiers 2022 report recorded peaks of 119 dB, the highest of any city it surveyed.

### How loud is Moradabad?
_Source: https://decibelshield.app/sound-map/moradabad/_

Moradabad, India’s “Brass City,” ranked second-loudest in the UNEP Frontiers 2022 survey with recorded peaks of 114 dB. Estimated daytime levels of 75–92 dB combine dense traffic with the hammering of thousands of brass workshops embedded in residential neighbourhoods.

### How loud is Delhi?
_Source: https://decibelshield.app/sound-map/delhi/_

Delhi’s busy corridors run an estimated 75–90 dB by day — roughly 25–35 dB above the WHO road-noise guideline. Horn-heavy traffic is the engine of it, with festival firecrackers and construction layered on top, despite some of India’s most detailed noise rules.

### How loud is Cairo?
_Source: https://decibelshield.app/sound-map/cairo/_

Cairo’s estimated 75–90 dB daytime range traces to a famous finding: a 2007 Egyptian National Research Centre study measured average downtown noise around 85 dB — like spending the day inside a factory. Traffic horns, street commerce and dense, hard-walled streets keep it there.

### How loud is Mumbai?
_Source: https://decibelshield.app/sound-map/mumbai/_

Mumbai’s main corridors run an estimated 74–88 dB by day. The city pairs India’s standard horn-heavy traffic with festival seasons — Ganesh Chaturthi processions have been measured above 100 dB by the Awaaz Foundation — and answers back with some of India’s most active anti-noise enforcement.

### How loud is Kolkata?
_Source: https://decibelshield.app/sound-map/kolkata/_

Kolkata’s dense core runs an estimated 73–88 dB by day, driven by buses, taxis and reflexive honking on narrow colonial-era streets. West Bengal counters with India’s strictest firecracker noise cap and designated no-horn zones — enforcement, as everywhere in India, is the variable.

### How loud is Karachi?
_Source: https://decibelshield.app/sound-map/karachi/_

Karachi’s arterial roads run an estimated 73–87 dB by day. Published studies of corridors like Shahrah-e-Faisal report roadside averages in the 80s, driven by buses, rickshaws and trucks — well above Pakistan’s legal 55 dB residential day limit, with enforcement chronically thin.

### How loud is Ho Chi Minh City?
_Source: https://decibelshield.app/sound-map/ho-chi-minh-city/_

Ho Chi Minh City runs an estimated 72–87 dB by day, powered by one of the planet’s great motorbike fleets — millions of them — plus a karaoke culture so loud it became the city’s top complaint category. UNEP’s 2022 survey recorded peaks of 103 dB.

### How loud is Kathmandu?
_Source: https://decibelshield.app/sound-map/kathmandu/_

Kathmandu runs an estimated 72–85 dB by day in its traffic corridors — UNEP’s survey measured 100 dB at Kupondole. The valley’s 2017 horn ban remains South Asia’s most famous noise intervention: it worked, audibly, and much of it has held.

### How loud is Lagos?
_Source: https://decibelshield.app/sound-map/lagos/_

Lagos runs an estimated 71–85 dB by day — danfo buses and horns by day, and a uniquely Lagosian layer at all hours: tens of thousands of private generators bridging grid failures, plus amplified worship loud enough that the state environmental agency seals dozens of venues a year.

### How loud is Hanoi?
_Source: https://decibelshield.app/sound-map/hanoi/_

Hanoi runs an estimated 71–85 dB by day: millions of motorbikes on Old Quarter streets built for none, construction for an expanding metro, and a public-loudspeaker network dating to wartime that the city debated switching back on citywide in 2022.

### How loud is Manila?
_Source: https://decibelshield.app/sound-map/manila/_

Metro Manila runs an estimated 70–85 dB by day. Jeepneys — diesel, open-sided, thousands strong — set the traffic baseline along EDSA and the city’s arteries, while videoke systems dominate the after-hours complaint files of barangay halls across the capital.

### How loud is Bangkok?
_Source: https://decibelshield.app/sound-map/bangkok/_

Bangkok runs an estimated 70–84 dB by day — UNEP’s survey recorded 99 dB peaks. Un-silenced motorbikes, tuk-tuks and elevated traffic stack over street markets, against a national ambient standard of 70 dB that central corridors regularly breach.

### How loud is Jakarta?
_Source: https://decibelshield.app/sound-map/jakarta/_

Jakarta runs an estimated 70–84 dB by day: one of the world’s largest motorbike fleets idling and surging through chronic congestion, layered with construction and, distinctively, a 2022 national circular asking mosques to cap loudspeaker volume at 100 dB.

### How loud is Istanbul?
_Source: https://decibelshield.app/sound-map/istanbul/_

Istanbul runs an estimated 69–83 dB by day across its loudest corridors. The Mimi Worldwide Hearing Index placed it among the noisiest cities measured; a construction boom, nightlife districts and Bosphorus-spanning traffic keep the pressure on, under EU-style noise mapping rules.

### How loud is Guangzhou?
_Source: https://decibelshield.app/sound-map/guangzhou/_

Guangzhou runs an estimated 69–82 dB by day. The 2017 Mimi Worldwide Hearing Index rated it the worst of 50 world cities for noise pollution; China’s 2022 Noise Pollution Prevention Law now targets exactly its mix of traffic, construction and dense-city living.

### How loud is Mexico City?
_Source: https://decibelshield.app/sound-map/mexico-city/_

Mexico City runs an estimated 68–82 dB by day. Beyond the traffic of 9 million vehicles, its signature is amplified street commerce — the recorded “fierro viejo” scrap-buyer chant, tamale loudspeakers, organ grinders — regulated on paper by the city’s NADF-005 noise norm.

### How loud is New York?
_Source: https://decibelshield.app/sound-map/new-york/_

New York runs an estimated 68–81 dB on its loud corridors — UNEP’s survey recorded 95 dB peaks. Noise is reliably the city’s top 311 complaint; the response spans America’s first big-city noise code (1972) to today’s automated noise cameras ticketing loud exhausts.

### How loud is São Paulo?
_Source: https://decibelshield.app/sound-map/sao-paulo/_

São Paulo runs an estimated 68–80 dB by day. Its anti-noise apparatus is distinctive: PSIU, the city’s dedicated silence-enforcement program, has fined and shuttered venues since the 1990s, while the largest urban helicopter fleet on earth adds a noise layer few cities share.

### How loud is Buenos Aires?
_Source: https://decibelshield.app/sound-map/buenos-aires/_

Buenos Aires runs an estimated 67–80 dB by day, with the 20-lane Avenida 9 de Julio as its roaring centrepiece. The city legislated early — Law 1.540 (2004) governs urban noise — and its colectivo bus fleet and football nights supply the signature peaks.

## Sound measurement FAQ

### Can I measure noise from my neighbors for a complaint?
_Source: https://decibelshield.app/faq/measure-neighbor-noise-complaint/ (updated 2026-06-09)_

Yes — phone or browser readings are useful for documenting a pattern, but they're rarely accepted as formal evidence because the devices aren't calibrated. Log dates, times and levels consistently, check your local noise ordinance's limits, and request an official measurement if escalation is needed.

## What app readings can and can't do

An uncalibrated reading from a phone or browser won't usually stand as evidence in court or code enforcement, because the measurement chain isn't certified. What it *does* do well is establish a **pattern**: a log showing 30 nights of 70 dB bass after 11pm tells a property manager or mediator a clear story, even with ±5–10 dB of uncertainty on each entry. Tools: the [online meter](/) for spot checks, or an app with measurement history like [Decibel Shield](/app/) so each entry is time-stamped automatically.

## Know what your ordinance actually says

Noise rules are local and specific. Most city codes set limits like "X dB(A) at the property line" or "at the complainant's window," often with stricter night-time numbers (commonly 10 dB lower after 10 or 11pm), and many regulate by nuisance standard ("plainly audible at 50 feet") rather than decibels at all. Search your city's municipal code for "noise" before assuming a number — a reading that seems damning may be legal, and vice versa.

## A documentation routine that works

1. Measure from the same spot, same way, each time — consistency beats precision.
2. Record date, time, duration, reading, and what the noise was.
3. Note the quiet baseline level at the same spot for contrast.
4. Keep communication records with the neighbor and any complaints filed.
5. If the city investigates, code officers bring calibrated meters — your log tells them when to come.

## Keep it neutral

This is documentation guidance, not legal advice; rules differ by city and country. For what the numbers mean physically, see the [decibel levels chart](/decibel-levels-chart/) and [what levels are dangerous](/faq/what-decibel-level-is-dangerous/).

### Can your iPhone measure decibels accurately?
_Source: https://decibelshield.app/faq/can-iphone-measure-decibels/ (updated 2026-06-09)_

Yes, within limits. NIOSH researchers found that the best iOS sound meter apps read within about ±2 dB of professional reference meters in lab tests — good enough for awareness and exposure screening. Phone microphones still struggle with very loud peaks and are not a legal substitute for a calibrated SPL meter.

## What the research actually says

The most-cited evidence comes from NIOSH researchers Chucri Kardous and Peter Shaw, who tested smartphone sound measurement apps against calibrated laboratory reference systems. Their findings: a handful of well-built iOS apps measured within roughly **±2 dB(A)** of the reference — comparable to the tolerance of a Type 2 field meter — and accuracy improved to about ±1 dB when an external calibrated microphone was used. That research is the reason the free [NIOSH Sound Level Meter app](https://www.cdc.gov/niosh/noise/about/app.html) exists at all: iPhones have consistent enough audio hardware that a carefully calibrated app can do real screening work.

## Why iPhones do better than Android here

Apple ships a small number of hardware models with tightly controlled microphone components, so an app can ship per-model calibration profiles. Android spans thousands of devices with wildly different microphones, which is why the NIOSH app shipped on iOS only.

## Where phones still fall short

Phone microphones are built for voice. They roll off very low frequencies, and at high levels — sustained sound above roughly 100 dB — they can compress or clip, under-reading the true level. Wind, cases, and where you hold the phone all add error. For anything legal, occupational, or contractual, you need a calibrated meter that meets IEC 61672 — see [how phone apps compare to dedicated SPL meters](/faq/phone-vs-dedicated-spl-meter/).

## Try it now

You can estimate your current noise level with the [free online decibel meter](/) right in your browser, or get calibrated readings, history, and exposure alerts with [Decibel Shield for iOS](/app/).

### Do I need an external mic for accurate phone measurements?
_Source: https://decibelshield.app/faq/external-mic-for-phone-measurements/ (updated 2026-06-09)_

For awareness and everyday exposure tracking, no — a good app on the built-in mic gets within a few dB. For measurements you'd defend to anyone else, yes: NIOSH research found phone apps paired with calibrated external microphones matched professional meters within about ±1 dB.

## What the built-in mic gets you

Phone microphones are consistent enough — especially on iPhones, where models share tightly specified components — that well-calibrated apps land within a few dB of the truth at conversational-to-loud levels. NIOSH's app testing showed the best iOS apps within about ±2 dB(A) in lab conditions on internal mics. For checking your gym class, your commute, or your kid's concert, that's all the accuracy the decision needs.

## What an external mic changes

A calibrated external microphone (typically $15–100, plugging into Lightning/USB-C or the headset jack) replaces the weakest link in the chain. In the same NIOSH research, apps using calibrated external mics agreed with reference instruments within roughly **±1 dB** — Type 2 meter territory. You also escape the phone's voice-optimised mic placement and any residual OS processing on the built-in path.

## When it's worth it

- You take readings you'll share with a landlord, venue, or employer and want them defensible-ish (a real Class 2 meter is still the standard for formal disputes).
- You measure quiet environments (below ~35 dB), where phone mic self-noise dominates.
- You measure loud events (above ~100 dB), where built-in mics start compressing the truth away.

## When it isn't

If the question is "should I wear earplugs here?" or "is the baby's room quiet enough?", the answer arrives just as reliably from the [online meter](/) or the built-in mic with [Decibel Shield](/app/). Spend the money on good earplugs instead — they solve the problem the meter only describes.

### How accurate are phone decibel meters vs. dedicated SPL meters?
_Source: https://decibelshield.app/faq/phone-vs-dedicated-spl-meter/ (updated 2026-06-09)_

A dedicated Class 2 SPL meter is accurate to about ±1.5 dB by standard; good phone apps tested by NIOSH came within ±2 dB in lab conditions, but uncalibrated phone or browser readings can drift 5–10 dB in the real world. Phones are for awareness; calibrated meters are for evidence.

## The accuracy ladder

From most to least accurate:

| Tool | Typical accuracy | Standard |
|---|---|---|
| Class 1 sound level meter | ±1 dB | IEC 61672 Class 1 |
| Class 2 sound level meter | ±1.5–2 dB | IEC 61672 Class 2 |
| Phone app with calibrated external mic | ±1–2 dB | NIOSH lab testing |
| Well-built phone app, internal mic | ±2–5 dB | NIOSH lab testing (best apps) |
| Browser-based meter (like ours) | ±10 dB | uncalibrated estimate |

The NIOSH lab numbers are the optimistic case: controlled environment, pink noise, phone held correctly. Out in the world — wind, reflections, a case over the mic, auto gain you can't see — uncalibrated readings drift further.

## What calibration actually does

A dedicated meter is calibrated end-to-end: its microphone capsule, preamp, and weighting filters are checked against a known reference tone (usually 94 dB at 1 kHz from an acoustic calibrator). A phone app can only apply a software offset on top of whatever the device's microphone hardware and OS processing do — better than nothing, much better with a per-model profile, but never traceable the way a real meter is.

## When each is the right tool

- **Browser meter:** instant answer to "roughly how loud is it here?" — [try it now](/).
- **Phone app:** day-to-day exposure awareness, history, trends. [Decibel Shield](/app/) adds Apple Health sync and background measuring.
- **Dedicated SPL meter:** noise complaints with legal weight, occupational compliance (OSHA/NIOSH), product testing, anything someone might dispute.

## Why our readings say "±10 dB"

We publish the honest number for an uncalibrated browser meter rather than implying instrument precision. [Why apps disagree with each other](/faq/why-do-decibel-apps-differ/) covers where the variance comes from.

### How loud is too loud for headphones?
_Source: https://decibelshield.app/faq/how-loud-is-too-loud-headphones/ (updated 2026-06-09)_

Keep headphones at or below about 80 dB(A) for up to 40 hours a week — the WHO's safe-listening allowance. Most phones can exceed 100 dB at maximum volume, where safe time is minutes. A practical rule: if someone beside you can hear your music, it's too loud.

## The numbers that matter

The [WHO](https://www.who.int/news-room/fact-sheets/detail/deafness-and-hearing-loss) and ITU's safe-listening standard works like a weekly budget: about **80 dB(A) for 40 hours**. Go louder and the budget drains fast — at 95–100 dB, typical of maximum volume on many phones with stock earbuds, you can spend a full week's allowance in well under an hour. The WHO estimates over a billion young people are at risk of hearing loss from unsafe listening habits, mostly headphones and venues.

## What your phone already tracks

iPhones log headphone audio levels in the Health app and notify you when your 7-day exposure crosses the safe-listening limit, using reasonably accurate output estimates for Apple and many certified headphones. Android offers volume warnings above regulatory thresholds. These system numbers are more trustworthy than any microphone app for *headphone* exposure, because the phone knows its own output level — a mic can't hear inside your ear canal.

## Practical rules that hold up

- **The 60/60 rule:** no more than 60% volume for no more than 60 minutes at a stretch is a reasonable approximation for most phone-and-earbud combos.
- **The bystander test:** audible to the person next to you means too loud.
- **Noise-cancelling helps:** cutting background noise lets you listen 10+ dB quieter on transit — often the single biggest exposure win.
- **Ringing is damage:** muffled hearing or tinnitus after listening means you exceeded your dose. It may recover; the cells don't fully.

## Know your environment too

Headphone dose stacks on top of ambient exposure. Check what your surroundings contribute with the [online decibel meter](/), see [what levels are dangerous](/faq/what-decibel-level-is-dangerous/), or track your daily exposure automatically with [Decibel Shield for iOS](/app/) and Apple Health.

### What decibel level is dangerous for hearing?
_Source: https://decibelshield.app/faq/what-decibel-level-is-dangerous/ (updated 2026-06-09)_

Hearing damage risk starts at 85 dB(A) averaged over 8 hours, per NIOSH. Every 3 dB louder halves the safe time: 88 dB is safe for 4 hours, 100 dB for 15 minutes. At 120 dB and above — sirens, fireworks at close range — damage can be immediate.

## The 85 dB rule and the 3 dB trade

[NIOSH](https://www.cdc.gov/niosh/noise/about/noise.html) — the US occupational health research agency — sets its recommended exposure limit at **85 dB(A) as an 8-hour time-weighted average**. The scale is logarithmic, so safe time halves every 3 dB:

| Level | Safe exposure (NIOSH) | Sounds like |
|---|---|---|
| 85 dB | 8 hours | city traffic, lawn mower |
| 88 dB | 4 hours | busy kitchen at rush |
| 94 dB | 1 hour | riding a loud subway |
| 100 dB | 15 minutes | car horn at 5 m, club dance floor edge |
| 110 dB | under 2 minutes | chainsaw, front rows of a concert |
| 120 dB+ | none — immediate risk | siren up close, fireworks |

OSHA's *legal* workplace limit is higher (90 dB with a 5-dB exchange rate), but NIOSH's 85 dB recommendation is the health-protective number — and the one hearing researchers use.

## It's the dose, not just the volume

Noise damage works like sunburn: intensity × time. One loud concert and a full workweek at 85 dB can deliver a comparable dose. That's why the WHO recommends tracking a weekly sound allowance — roughly 80 dB(A) for 40 hours — and why Apple's Health app warns you about weekly headphone exposure rather than single spikes. See [how loud is too loud for headphones](/faq/how-loud-is-too-loud-headphones/).

## What to do at each level

Below 70 dB: no risk at any duration, per the EPA's long-standing guidance. 70–85 dB: fine for normal daily life. 85–100 dB: limit time or wear earplugs. Above 100 dB: protection on, or leave.

## Check where you are right now

Run the [free online decibel meter](/) for an estimate, or see the [full chart of common sounds](/decibel-levels-chart/) with sourced levels for 30+ situations.

### What does dB(A) mean?
_Source: https://decibelshield.app/faq/what-does-dba-mean/ (updated 2026-06-09)_

dB(A) is a decibel reading filtered to match human hearing, which is less sensitive to very low and very high frequencies. The A-weighting curve trims those extremes — a 60 Hz hum measures far lower in dB(A) than its raw level. Nearly all noise regulations and exposure limits are written in dB(A).

## Why weighting exists

A microphone hears all frequencies almost equally. Human ears don't: at moderate listening levels we're most sensitive between roughly 1–4 kHz (where speech lives) and much less sensitive to deep bass and the highest treble. An unweighted meter would tell you a 50 Hz transformer hum is as "loud" as a 1 kHz alarm of the same pressure — your ears disagree.

## What the A-curve does

A-weighting applies a standard filter (defined in IEC 61672) derived from the ear's equal-loudness response at moderate levels. Relative to 1 kHz, it cuts about 19 dB at 100 Hz, about 30 dB at 50 Hz, boosts slightly around 2–3 kHz, and rolls off again above 10 kHz. A reading taken through that filter is written **dB(A)** or dBA, and most measurements you encounter — NIOSH's 85 dB limit, city noise ordinances, the readout on a building-site meter — are A-weighted.

## Other weightings you'll see

**C-weighting (dB(C))** stays nearly flat across bass frequencies and is used for peak measurements of loud impulsive sound — gunfire, fireworks, concert subwoofers. **Z-weighting** is no filter at all. If a spec just says "dB" with no letter, it usually means dB(A) in a regulatory context, but it's worth confirming.

## Our tools

The [online decibel meter](/) has an A-weighting toggle — it's an approximation built from standard biquad filters, and the readout label switches to dB(A) when it's on. The [Decibel Shield iOS app](/app/) uses device-tuned level corrections rather than a formal weighting filter, so treat its readings as unweighted estimates when comparing against dB(A) limits.

### Why do decibel apps show different readings?
_Source: https://decibelshield.app/faq/why-do-decibel-apps-differ/ (updated 2026-06-09)_

Because each app guesses differently about uncalibrated hardware. Different microphones, hidden OS processing like auto gain, different calibration offsets, A-weighting versus none, and different averaging windows can stack up to 5–10 dB of disagreement between two apps measuring the same sound.

## The five sources of disagreement

1. **Microphone hardware.** Every phone model's mic has its own sensitivity and frequency response. The same app on two phones can read several dB apart before software even starts.
2. **OS audio processing.** Phones quietly apply auto gain control, noise suppression, and echo cancellation tuned for calls. An app that doesn't explicitly disable these is measuring a signal the OS already altered. (Our [browser meter](/) disables all three.)
3. **Calibration offset.** Converting a digital signal level (dBFS) to sound pressure level (dB SPL) requires an offset that depends on the exact microphone. Apps ship different per-model profiles — or one global guess.
4. **Weighting.** One app shows raw dB, another shows [dB(A)](/faq/what-does-dba-mean/). On bass-heavy noise those can differ by 10 dB or more by design, not by error.
5. **Averaging window.** "Fast" (125 ms), "slow" (1 s), peak-hold, or a smoothed UI number — each responds differently to fluctuating noise, so simultaneous readouts won't match.

## How to get comparable readings

Use one app, on one device, with the same weighting and averaging every time — relative comparisons ("the bedroom is 12 dB quieter than the street") survive calibration error even when absolute numbers drift. For absolute accuracy, calibrate against a reference: NIOSH's research found apps with calibrated external microphones land within about ±1 dB of professional meters.

## The honest baseline

No uncalibrated app — ours included — should promise instrument precision. That's why the [online meter](/) labels every reading an estimate (±10 dB), and why apps that ship device corrections and let you fine-tune against a reference — like [Decibel Shield](/app/) — get closer to the truth than a generic browser reading can.

## Decibel Shield - dB Meter (iOS app)
_Source: https://decibelshield.app/app/_

Free iOS sound meter by APPSTACK LLC (App Store ID 6461600902, iOS
15.6+): real-time dB readout with VU meter, measurement history
with iCloud sync, Apple Health integration (premium), exposure trends,
threshold alerts, location tagging, background measuring, sound
classification, CSV export, and noise/nature sounds. 4.7★
across 528 App Store ratings as of 2026-06-09. No
ads. Premium is $44.99/year after a 7-day free trial.

## About
_Source: https://decibelshield.app/about/_

Run by APPSTACK LLC, the independent studio behind Decibel Shield - dB Meter. The meter
records nothing; every published stat is sourced or marked as our own
measurement; the site carries no ads. Corrections ship within a week.