How We Test

Tones are synthesised by oscillators at the device sample rate, noise from random buffers with standard filters for pink, brown, blue and violet.

Mic tools compute RMS and peak in dBFS. The decibel meter maps dBFS to an estimated SPL with a user offset; without calibration readings can be off by 5–10 dB.

LUFS uses a K-weighting approximation and BS.1770 gating; file analysis decodes and filters offline.

A YIN-style autocorrelation runs on 4096-sample blocks with parabolic interpolation.

We compare outputs with reference tones and spectrum analysis in desktop software, and check tuners against known frequencies.

Browsers cannot read microphone sensitivity or speaker output, so no web tool can give calibrated SPL or hearing levels.

• About us

Reference-only tools

Our meters provide relative readings; use a certified meter for legal or occupational decisions.

Top error sources and fixes

Automatic gain, phone cases, wind and distance cause most errors; disable processing, remove the case, shield from wind and keep distance fixed.

Calibration offset and verification

Set an offset against a reference meter, then verify at a second level.

Device and browser matrix

Results vary between browsers because each applies different processing to microphone input.

Why dBFS is not SPL

Digital level depends on microphone sensitivity, which browsers do not expose.

What a browser cannot measure

Absolute SPL, hearing level in dB HL, true multichannel decoding and hardware latency in isolation.

Make comparisons repeatable

Same device, position, settings and duration every time.

What the meter measures

RMS level from the microphone stream converted to dB with an optional offset.

Why accuracy varies and how to reduce error

Device, browser processing and placement; fix placement and disable processing.

Algorithm summary

Short-block RMS, exponential smoothing, min/avg/max tracking; LUFS uses weighting and gating.

Verification evidence

Side-by-side comparisons with a reference meter and known test signals.

Known limitations

No absolute calibration, no multichannel guarantees, and hearing results are relative.

Typical checks and safe use

Start at low volume and stop if anything is uncomfortable.

Output tests

Speaker and headphone signals are generated exactly; what you hear depends on the device.

Latency, surround and hearing demonstrations

These depend on OS buffers, channel routing and headphones.

Where thresholds come from

Exposure limits follow NIOSH and WHO guidance; hearing bands follow audiology conventions.

Different browsers, different readings

Each browser applies its own input processing and sample handling.

Digital levels (dBFS) describe the signal inside the device. Sound pressure (dB SPL) describes air pressure in the room. Converting one to the other requires knowing the microphone's sensitivity, which browsers do not expose, so our meters estimate and never claim calibration.