This tool uses the modern browser's built-in Web Audio API and getUserMedia interface to capture real-time audio data from the microphone, calculate the root mean square (RMS) amplitude of the audio signal, and map it to a relative decibel value from 0 to 100. Although it is not an absolute sound pressure level (dB SPL), it accurately reflects the relative change trend of ambient volume, suitable for daily noise monitoring, microphone testing, sound intensity comparison, and more. Whether for office noise assessment or home audio debugging, the online decibel meter provides intuitive visual feedback.
The operation is very simple: click the "Start Detection" button, follow the browser prompt to allow microphone access, and you will instantly see the decibel value, dynamic progress bar, statistics, and real-time line chart. Click "Stop Detection" to end the current detection session while retaining the statistics; click "Reset Data" to clear the current statistics and chart without stopping detection (if you need to start fresh, stop first then start again). The chart supports PNG export for easy saving or sharing of volume trends.
First-time use requires granting microphone permission; the browser will show a permission request. If accidentally denied, click the address bar icon to re-allow, or refresh the page and click start detection again. This tool does not record or upload any audio data; all processing is done locally, protecting user privacy.
This tool supports major browsers such as Chrome, Edge, Safari, and Firefox, and can also be used on mobile phones and tablets (system microphone permission required). It is recommended to use in a relatively quiet environment for more accurate relative readings.
Online decibel detection is not only an interesting tech demonstration but also offers multiple practical values:
Although this tool displays relative decibels (simulated dB), after auditory curve calibration, the values roughly correspond to the following scenarios:
| Relative Decibel Value | Corresponding Environment Reference | Subjective Feeling |
|---|---|---|
| 0~15 dB | Quiet late-night room, recording studio | Almost silent |
| 15~35 dB | Library, countryside night | Very quiet |
| 35~55 dB | Quiet office, soft conversation | Comfortable |
| 55~75 dB | Normal conversation, background music | Normal communication |
| 75~90 dB | Busy street, vacuum cleaner | Somewhat noisy |
| 90~100 dB | Shouting, close-range speakers | Loud, may damage hearing over time |
Note: Due to differences in microphone sensitivity across devices, the values are for reference only and are not recommended for professional acoustic measurements. For precise data, please use a calibrated sound level meter.
The online decibel meter is implemented purely with HTML5 + JavaScript front-end technology. The microphone stream is analyzed locally and never leaves your device. There is no server upload or audio storage, so users can use it with confidence. The new chart and statistics features make data changes clear at a glance, and PNG export facilitates recording and analysis.
Q: Why is there no response after clicking "Start Detection"?
A: Please check whether you are accessing via HTTPS (or localhost); browser security policies require a secure context to access the microphone. This tool strictly follows user gesture triggering.
Q: The decibel value fluctuates wildly?
A: Instantaneous volume naturally fluctuates significantly. The tool has a built-in mild smoothing algorithm, and the chart records at 200ms intervals to reflect real dynamics.
Q: Can it be calibrated to absolute decibels?
A: True sound pressure level requires professional calibration equipment and a fixed sound pressure reference, which is difficult to achieve on a web page. This tool focuses on relative measurement and trends.
Q: How to export the chart?
A: Click the "Export as PNG" button to save the current trend chart as an image, which will be automatically downloaded to your device.
OkeyTool.com is dedicated to providing free, convenient online utility tools. In addition to the online decibel meter, you can also find microphone test, online recording, audio format conversion, waveform visualization and other tools under the "Audio Tools" category. All tools require no registration or download, just click and use. Feel free to bookmark this site and solve your needs anytime, anywhere.
Tip: For a better detection experience, it is recommended to use the tool in a relatively quiet environment and avoid wind noise or blowing directly into the microphone.