Noise Pollution Meter
Read your microphone’s level in real time with a traffic-light health-risk indicator keyed to published WHO, EPA and NIOSH noise guidance, a recommended maximum safe exposure duration at the current level, and an exportable noise-observation note.
⚠️ This is not a sound-level meter and the reading is not legal evidence. A phone/laptop mic is uncalibrated, so a browser can only honestly show relative dBFS until you calibrate it against a real meter — the dB SPL figure and risk colour are then an uncalibrated estimate, not a certified reading and not valid for any complaint, dispute, or compliance use. The estimate is also unweighted (flat / Z-weighted), not A-weighted, so it only approximates a dB(A) meter for broadband sounds near the calibration condition. The WHO/EPA/NIOSH values shown are real published guidance, cited for orientation only. Nothing is recorded or uploaded.
Microphone
We request raw audio with automatic gain control, noise suppression and echo cancellation off — otherwise the level is meaningless. Audio is analysed live and never recorded or sent.
Calibration shared
Hold a real sound-level meter (or a calibrated phone app) next to your mic, read its current level, and type it here while this tool is running. The offset is stored once and reused by every Noise tool on the site. Note: this tool’s estimate is unweighted (flat), so it matches an A-weighted meter best on broadband sound.
Export
A local text download labelled indicative only — not legal, complaint, or compliance evidence.
Current level
Leq / Lmax / L90 are valid as relative metrics; shown as estimated dB SPL (unweighted, not A-weighted) only once calibrated. WHO ~55 dB(A) day / ~40 dB(A) night; EPA 70 dB(A) 24-h; NIOSH 85 dB(A) / 8 h are cited published guidance, not a verdict.
How It Works
This tool measures the RMS energy of your microphone signal every animation frame and smooths it over about a second (a “slow” meter response). The raw result is in dBFS — decibels relative to digital full scale, where 0 is the loudest the system can capture and quieter sounds are negative. A web browser receives only a normalised digital signal: it has no idea how sensitive your particular mic is, how far the source is, or what gain the OS applied. So out of the box this is a relative measurement, honest for comparisons (louder vs quieter, before vs after) but not an absolute environmental decibel value.
To show a meaningful dB SPL number you must calibrate. Stand a real sound-level meter or a calibrated phone app next to your mic, read its current level, and type that into the calibration box while this tool is running. The tool stores a single offset (known − measured dBFS) under the shared key fd-noise-cal, so every Noise tool on the site reuses it — calibrate once, and the whole category gives the same estimate. Even then the figure is an uncalibrated estimate: it drifts with distance, mic position and the spectrum of the sound, and it is never a substitute for a Type 1/2 meter. It is also unweighted (flat / Z-weighted) — the tool does not apply the A-weighting curve, so it only matches an A-weighted meter when the source spectrum resembles the calibration spectrum, and it over-reads low-frequency-dominated sources (HVAC rumble, distant traffic) relative to a true dB(A) reading.
Once calibrated, the colour traffic light compares your estimated level against published guidance: green below about 55 dB(A) (the WHO daytime outdoor community-noise guideline), amber up to 70 dB(A), orange up to 85 dB(A) (around the EPA’s 70 dB(A) 24-hour average to prevent measurable hearing loss), and red at or above 85 dB(A), the NIOSH occupational limit. The recommended max exposure applies the NIOSH rule of 8 hours at 85 dB(A) with a 3 dB exchange rate (every extra 3 dB halves the safe time). These thresholds are real published values; the comparison is for personal orientation, not a legal or medical judgement.
One physical caveat: consumer mics roll off at the frequency extremes and generally cannot capture true infrasound (<20 Hz) or deep sub-bass, so low-frequency sources (HVAC rumble, distant traffic, machinery) may read lower than they feel. Spectral shape and before/after comparisons with the same mic and setup remain trustworthy even uncalibrated.