Decibel Dossier: Sound Meter

By: 秋林周

Noise level meter & dB report

Features & Capabilities

Measure noise, see how it compares to NIOSH/OSHA hearing-safety limits, and generate a signed PDF report you can verify by QR. Local, no account, free to measure.

Decibel Dossier turns your iPhone into a sound level meter that not only measures noise, but records it and produces a verifiable report.

Measure Real-time sound pressure level in dB(A) and dB(C), with Leq (equivalent level), max/min, L10/L90 statistics, a live spectrum and a time history.

Hearing safety Your reading is compared against NIOSH and OSHA occupational-noise references: a hazard level (safe / moderate / hazardous) and the recommended safe exposure time at the current level (for example, about 8 hours at 85 dBA, halving every 3 dB). A quick reference chart shows how the level compares to everyday sounds.

Report Generate a structured PDF report containing the measurement details, capture device and calibration status, statistics, the hearing-safety assessment, and a disclaimer. Each report carries a digital-signature QR code, so anyone receiving it can scan and confirm the key fields have not been altered.

Records Every measurement is saved on your device. Review history, add the location and noise source, and export at any time.

Privacy Measurement, statistics and reports are all processed on your device. The microphone audio is converted to a sound level in real time and discarded; no recordings are stored, nothing is uploaded, and there is no account.

Free to measure; exporting a watermark-free report requires a one-time purchase (a single report or a lifetime unlock).

Note: this is a consumer measurement tool. A phone microphone is not a certified measuring instrument, and readings depend on the device, environment and how you hold it. Results are for reference and are not a legal or occupational-health determination. For a measurement with legal standing, use a calibrated Type 1/2 sound level meter or a qualified professional.