Sound level measurement methodology and limitations

How the estimate is produced

After microphone permission is granted, the Web Audio API reads short samples from the selected microphone. SoundLevelTest calculates the root mean square of each sample window, converts that signal level logarithmically, applies the selected calibration offset, and displays an estimated dB SPL value. Audio samples are discarded after analysis.

The live display also derives minimum, maximum, and average values from the estimates observed during the current session. Resetting the statistics starts those summaries again; stopping or leaving the page ends the microphone stream.

Calibration and limitations

SoundLevelTest provides an estimated sound level based on microphone input from the device running the browser. Built-in microphones and browser audio paths are not calibrated to one universal reference, so readings can vary by device, microphone, distance, orientation, environment, and software processing.

A calibration offset can align one device more closely with a trusted reference under the same conditions. It does not calibrate the microphone across every frequency, level, browser, or environment, and it does not convert the device into a standards-compliant instrument.

These browser-based readings should not be treated as measurements from a calibrated Class 1 or Class 2 professional sound level meter.

Manual browser testing

SoundLevelTest has been manually tested on an iPhone 15 Pro with Safari, a MacBook Pro with Chrome, a Google Pixel with Edge, and a Windows desktop with an external USB microphone. These checks verify browser functionality across different environments; they do not establish universal measurement accuracy.

The exact Pixel model, operating-system versions, browser versions, USB microphone model, and test dates have not yet been documented publicly.

Maintainer

This methodology is maintained by Nayeem. Corrections can be sent through the contact page.