STILL / FIELD NOTES 03

Reference adjustment for an iPhone sound meter

A reference adjustment aligns a reading with a suitable reference under specific conditions. It is not enough to type a number associated with a quiet room. Still requires an external reference for sound-pressure estimates and does not claim certified instrument performance.

September 8, 2026 · Arve Tech, maker of Still

Document the comparison

Record the reference instrument, its settings, the phone and input route, and the measurement conditions. Use a stable source and comparable positions. Follow the reference equipment's procedure; a phone speaker is not automatically a calibrated sound source.

Know what remains uncorrected

A single adjustment cannot establish frequency response, overload behavior or accuracy across the full level range. Changing the microphone or weighting can invalidate a previous match. Keep uncertain readings clearly labelled instead of treating the adjustment as a certificate.

Try a repeatable approach

1. Confirm both readings use compatible settings and units.
2. Compare under a stable, documented setup.
3. Save reference details and recheck when the setup changes.

Source and scope

NIOSH: Sound Level Meter app and measurement limitations

Measurement guidance is educational. Still is not a certified sound level meter and does not establish medical, legal or workplace-compliance conclusions. App-specific statements describe version 1.0.0, currently awaiting App Store review.