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Professional Noise Detector: A/C/Z Weighting, Spectrum Analysis, Data Export
Alert fires when dB(A) exceeds this level.
Press the start button to view visualization
Press the start button to view the real-time spectrum
Disclaimer: This tool uses the browser microphone and general algorithms to estimate noise levels. Results depend on an uncalibrated offset (default 94 dB SPL) and may vary by hardware. Not a substitute for a professional sound level meter.
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
Noise Meter Pro turns live microphone input into an approximate sound-level display. It shows three views of the same input: dB(A), dB(C), and dB(Z). A, C, and Z identify frequency-weighting curves: they change how frequency bands contribute to the displayed estimate. A-weighting reduces the contribution of some low and high frequencies; C-weighting retains more low-frequency contribution; Z is the flat, unweighted comparison. These are weighting labels, not separate microphones or different physical units.
The value is an estimate derived from the microphone signal with a fixed 94 dB reference offset. It is not calibrated to your particular microphone or room. Device processing, microphone response, distance, orientation, and background conditions can all affect what you see. Treat changes observed under the same setup as a relative comparison, not as a traceable sound-pressure measurement.
The live waveform shows the shape of the sampled signal over a short moment. The spectrum groups signal energy into frequency bands, with a log or linear frequency scale option. The graph helps spot where energy is concentrated; its peaks are not the average level of a recording. IEC 61672-1 defines performance requirements for specified sound level meters. Displaying weighting labels alone does not demonstrate compliance with that standard.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Open the tool in a browser that supports microphone access, then choose Start Monitoring. Allow microphone permission when prompted. A secure page and an available microphone are required.
Watch the large dial for the selected weighting. Choose dB(A), dB(C), or dB(Z) to switch the dial; the three smaller readouts let you compare all three estimates at once.
Use the waveform to watch signal changes and the frequency spectrum to inspect where energy is concentrated. Switch the spectrum between log and linear frequency scales when one view makes the pattern easier to inspect.
For a time-stamped numeric sample, keep monitoring active and select Start Recording. Add an optional note, then choose Stop and Save Recording. Open Records to inspect the saved summary or export a summary CSV, sample CSV, or JSON file.
For a useful before-and-after comparison, keep the device, microphone position, orientation, and surroundings as consistent as possible. Record what changed in the note. The saved sample file contains timestamps and A/C/Z values; it is not a playable audio recording.
Use cases
See how the tool fits into real work and everyday tasks.
Stand at the same marked position while a fan or air conditioner runs. Save a short sample before and after a repair or setting change, then compare the trend and spectrum as a troubleshooting clue.
A facilities or studio team can note the microphone position and room setup, then repeat a sample after moving equipment or adding a temporary barrier. Exported values help the team discuss whether the sound pattern changed.
Use a note to label a meeting, study session, or equipment test. A summary export is convenient for sharing session statistics; the sample export is better when someone needs to inspect the time sequence.
Q&A
Find concise answers to common questions and confusing cases.
Microphone sensitivity, frequency response, automatic processing, placement, and room conditions differ. Since this tool uses a fixed reference offset rather than calibration for each device, compare changes on the same device and setup instead of treating two devices as interchangeable meters.
No. The record summary's average is the arithmetic mean of sampled decibel values. It is not an energy-averaged LAeq measurement. Use a suitable calibrated instrument and the required method when an exposure or compliance metric is needed.
No audio playback file is created by the recording control. It saves timestamped A/C/Z numeric samples, summary statistics, the selected weighting, threshold details, and your optional note.
Notes
Review scope, result limitations, and important precautions before use.
This is an uncalibrated microphone-based estimate, not an IEC-compliant sound level meter, legal noise survey, workplace exposure assessment, or hearing-safety alarm. The status colors and adjustable threshold are interface cues only. Do not use them to decide that a loud environment is safe or to support a formal complaint or compliance finding. If a measurement has health, regulatory, or contractual consequences, use an appropriately calibrated instrument and the method required by the relevant authority or qualified professional.
Microphone access requires browser permission; the W3C media-capture specification describes the permission-based access model for local media. Saved numeric records are kept in this browser's local storage, up to 50 records. Clearing site data or changing browsers or devices can remove or make those records unavailable. Export anything you need to retain. The tool saves measurement samples rather than microphone audio.
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