📋 When to Use the Decibel Meter
It's handy whenever you want a quick sense of how loud a space is. Check whether a café, office, or co-working spot is quiet enough to concentrate; get a rough read on traffic, appliance, or street noise at home; see roughly how loud a concert, gym class, or power tool is so you can decide whether to wear hearing protection; or compare two rooms to find the quieter one. The colour zones give you an at-a-glance sense of whether a level is comfortable or worth protecting your ears from.
The important caveat: a phone or laptop mic isn't a calibrated instrument, and most apply automatic gain control that quietly adjusts levels — so treat the number as a ballpark, not a verdict, and expect it to read differently from one device to the next. For anything official — a workplace noise assessment, a legal noise complaint, an occupational-safety record — you need a calibrated, certified sound level meter, not a browser tab.
⚙️ How the Decibel Meter Works
Decibels are logarithmic, not linear, which is the key to reading them. Every 10 dB increase sounds roughly twice as loud and represents about ten times more sound energy — so 80 dB isn't "twice" 40 dB, it's vastly more intense. That's also why hearing risk climbs so fast: the safe exposure time drops sharply as the level rises.
Under the hood, the tool asks your browser for microphone access through getUserMedia and feeds the signal into the Web Audio API's AnalyserNode. Many times a second it reads the raw audio samples, calculates their RMS (root-mean-square, a measure of the signal's average energy), and converts that to a decibel value on a logarithmic scale. The audio is analysed entirely on your device and never leaves it — nothing is recorded or uploaded.
The Fast and Slow buttons change how quickly the reading reacts, mirroring the response settings on real sound level meters: Fast (~125 ms) follows sudden peaks like a door slam, while Slow (~1 s) averages things out for a steadier read of continuous noise. The peak-hold value remembers the loudest moment since you last reset it. Because consumer mics aren't calibrated to a reference level, the absolute number is an estimate — but the changes it shows, and the comparison between two spaces, are far more reliable than the exact figure.
How to Use the Decibel Meter
- Click 'Allow Microphone Access' when prompted by your browser.
- The meter begins measuring the ambient sound level in real time, displaying the current decibel reading.
- Watch the live waveform and peak level indicator to see sound intensity changes.
- Use the reference scale to understand what different dB levels mean (whisper, conversation, loud music, etc.).
Frequently Asked Questions
How accurate is it?
Think of it as an indicator, not an instrument. Because consumer microphones aren't calibrated and most phones apply automatic gain control, the absolute number can be off by a fair margin and will vary between devices. What it's good at is showing relative change — whether a room got louder or quieter, or which of two spaces is noisier. For an exact, trustworthy figure you need a calibrated sound level meter.
What do different decibel levels mean?
As rough benchmarks: around 30 dB is a whisper, 60 dB is normal conversation, 70 dB is busy traffic, 85 dB is where prolonged exposure starts to risk hearing damage, 100 dB is a loud concert, and 120 dB approaches the threshold of pain. The colour zones on the meter follow this rough scale — green for comfortable, shading toward red as levels get risky.
What's the difference between Fast and Slow?
They set how quickly the reading reacts, just like on professional meters. Fast (~125 ms) catches brief, sharp sounds such as a clap or a door slam. Slow (~1 second) smooths the reading out, which is better for judging steady background noise like traffic or an air conditioner without the number jumping around.
Is the noise around me dangerous to my hearing?
As a general guide, sustained exposure above about 85 dB can damage hearing over time, and the louder it gets, the less time it takes — so if the meter is sitting in the orange or red zone for long periods, it's worth using ear protection or moving away. Treat this as a prompt to be careful, not a medical assessment; if you have hearing concerns, see an audiologist.
Can I use this for a noise complaint or workplace report?
No. Official and legal noise measurements require calibrated, certified equipment and a defined measurement procedure, and an uncalibrated browser reading won't hold up as evidence. This tool is fine for your own awareness, but for a formal complaint or an occupational-safety record you'll need a proper sound level meter.
Is my audio recorded or sent anywhere?
No. The microphone signal is analysed live on your device to calculate the level and is never recorded, stored, or uploaded. When you stop the meter or close the tab, nothing remains.