Sound Decibel Meter - Sound Level Meter

Settings

Display Scale

"Positive" adds an offset to raw dBFS. "Negative" shows the actual dBFS value (usually below 0).

Frequency Weighting

Applies standard frequency weighting using FFT analysis to better reflect perceived loudness (dBA) or low-frequency content (dBC).

Display Update Rate

How often the display and graph update. Faster rates use slightly more CPU for UI rendering.

Peak Hold Time

How long the highest measured peak reading is displayed before potentially resetting.

Calibration Offset

Adjusts the displayed reading (+/- dB) for relative comparison.

Graph Type

Visual representation of the sound level or frequency content.

Accuracy Disclaimer: This tool measures relative sound levels in dBFS (decibels relative to full scale), the digital audio level captured by the microphone. Frequency weighting (dBA/dBC) is now applied using standard curves and FFT analysis for better relative accuracy, but it does NOT measure absolute dB SPL (sound pressure level) without external calibration. Readings remain highly dependent on the specific microphone, device gain settings, distance, and potential OS/browser audio processing. Use for general level indication and relative comparisons, not precise measurements. Disable system audio enhancements for best results.

Info & Troubleshooting

About This Tool

Online sound level meter that measure and analyze audio in real time using your device microphone. This tool provide advanced audio analysis with multiple measurement scales, real time visualization, and accurate sound measurements.

Understanding the Readings (dBFS vs. dB SPL)

Crucially, this meter shows dBFS (Decibels relative to Full Scale). This represents the digital signal level captured by the mic, where 0 dBFS is clipping. It is NOT dB SPL (Sound Pressure Level), which requires calibrated equipment. This work as any other mobile app you can find and developed daily to be accurate.

Factors affecting readings:

Microphone quality and frequency response.
Device internal gain/volume settings.
Distance and angle from the sound source.
Background noise.
Audio processing by your OS or browser (AGC, noise suppression, etc. - disable if possible!).

Use this meter for relative comparisons and general level awareness.

Accuracy & Calibration

Weighting (dBA/dBC/dBZ): dBA and dBC are implemented using standard frequency curves via FFT analysis for frequency accurate weighting *of the digital signal*. dBZ is flat (unweighted). While more accurate than simple simulation, the result is still relative dBFS.
Calibration Offset: Allows adding/subtracting a fixed dB value. Helps align the reading with a reference SPL meter *for a specific sound (e.g., 1kHz tone) at a specific distance*, but doesn't guarantee broad accuracy.
Clipping Indicator: Shows when the digital audio signal approaches 0 dBFS.
Min Reading Delay: The 'Min' reading starts calculating 1 second after measurement begins to ignore initial startup sounds.

Troubleshooting

Meter Not Starting / No Sound:
- Check microphone permissions (browser settings). Refresh page after granting permissions.
- Ensure correct mic is selected in OS settings.
- Close other apps using the mic.
- Refresh/restart browser.
Readings Seem Too High/Low (Overall Level):
- Adjust OS microphone input volume/gain.
- Change distance to source.
- Use Calibration Offset for relative adjustment.
Meter Stops Unexpectedly:
- Browser/OS might interrupt audio. Restart meter.
- Older devices might struggle with rapid updates or complex graphs. Try a slower update rate.
Performance Issues or Slowness:
- Try selecting a slower "Display Update Rate" in settings.
- The "Spectrum" and "Visualizer" graphs require more processing; switch to "History" or "Current Level" if performance suffers.
- Close unnecessary browser tabs or applications.

Tips for Best Readings

Crucial: Disable system audio enhancements (AGC, Noise Suppression, Echo Cancellation) if possible. If iOS we recommend add +10% to offset
Maintain consistent mic distance/orientation.
Be aware of background noise.

Reference Sound Levels (Approx. dB SPL)