Need a record of noise over time? This free noise monitor turns your phone or computer into a decibel logger. Set a limit, press Start and leave it running: it logs the sound level every second, records each event over your limit with its time, length and level, and gives you a CSV file and a report image. Use it for neighbour noise, construction, a noisy venue or checking a room overnight.
Noise Monitor & Decibel Logger
Log noise over minutes or hours. Set a limit, press Start and leave the device running: every loud event is recorded with its time, length and level, ready to download.
Microphone off. Sound is analysed on this device; nothing is recorded or uploaded.
- Average (Leq)
- –
- Background (L90)
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- Busy level (L10)
- –
- Loudest (Lmax)
- –
- Time over limit
- –
| # | Started | Length | Loudest | Average |
|---|---|---|---|---|
| No events yet. | ||||
Keep this page open and the device plugged in. Logging continues with the screen locked on most computers; phones may pause it, so keep the screen on. Readings are estimates from your device microphone; for official complaints you may need a certified sound level meter. Calibrate your microphone for better accuracy.
Related Tools
- Sound Decibel Meter
Check a sound's level right now.
- Background Noise Test
A quick test of a room's steady background noise.
- Decibel Chart
Put your logged levels in context.
- Noise Exposure Calculator
Work out a day's noise dose from loud periods.
- Volume Level Comparator
Compare the loud events with your background level.
How to Log Noise
- Put the device where the noise bothers you, for example the bedroom or the wall shared with a neighbour, and plug it in.
- Press Start logging and allow the microphone. Measure a minute of normal quiet first to see your background level.
- Set the limit about 10 dB above that background (or to the level in your local rules) and a minimum event length so short knocks are ignored.
- Add a note, such as the room and the source, then leave the page open. Logging continues if you switch tabs; on phones keep the screen on.
- Press Stop logging when you’re done and download the CSV (every second), the events CSV and the report image.
Understanding the Results
| Result | Meaning |
|---|---|
| Average (Leq) | The energy average of the whole log, the standard single number for noise over time |
| Background (L90) | The level exceeded 90% of the time: the quiet baseline between noises |
| Busy level (L10) | The level exceeded 10% of the time: the typical loud moments |
| Loudest (Lmax) | The single highest 1/8-second level |
| Events | Periods when the level stayed at or above your limit for at least the minimum length (gaps under 2 seconds are joined) |
The difference between the events and the background tells you how intrusive a noise is: something 10 dB above the background sounds about twice as loud (why decibels work that way). Levels are A-weighted, which matches how people hear (dB vs dBA).
Using a Noise Log for a Complaint
A log with dates, times, durations and levels is far more convincing than “it’s loud every night”. Keep a diary alongside it describing what you heard, and read apartment noise complaint levels for what counts as too loud. Councils, landlords and courts may still require measurements with a certified sound level meter, so use this log to show the pattern and decide whether to ask for an official assessment.
Choosing a Limit
- Night-time in a bedroom: the WHO guideline for sleep is about 30 dB(A) of continuous noise indoors; a limit of 35–45 dB(A) catches disturbing noise.
- Daytime at home: 45–55 dB(A) is typical; see room noise levels.
- Offices and classrooms: see office noise levels and classroom noise levels.
- Workplaces and construction: long exposure above 85 dB(A) is a hearing risk; see NIOSH and OSHA limits.
Accuracy and Practical Tips
Readings come from your device microphone, so they are estimates; calibrating once against a real meter makes them more reliable (link in the tool) and online decibel meter accuracy explains the limits. Keep the device still, away from its own fan noise, and don’t cover the microphone. How to measure decibels covers placement, and online meters vs apps compares the options.
Frequently Asked Questions
Does the noise monitor record audio?
No. It calculates levels from the microphone signal in your browser and stores only the numbers; no sound is recorded or uploaded.
How long can I log?
Up to 24 hours per session. The table shows the latest 50 events; the events CSV contains them all.
Can I use it to check workplace noise?
It gives a useful first picture of how loud a workplace is and for how long. Formal workplace assessments need a certified sound level meter or noise dosimeter, and the exposure limits above tell you when that matters.
Will it keep logging if I lock my phone?
Computers usually keep logging with the screen locked. Phones often pause the microphone when locked or when you switch apps, so keep the page open with the screen on and the phone charging.