SoniMeter: Sound Level Meter

Test how loud your restaurant is. Your neighbor's late-night party. Your concert. Your office HVAC. Your baby room.

Apple has no sound level meter for iPhone (the Watch one measures 3.4 dB low per published NIH research). The popular third-party apps charge around $40/year, push subscription prompts every launch, and read 28 dB in a completely silent room because their zero-calibration is broken.

Decibo is the noise meter those apps should have been. $3.99 once. No subscription. No ads. Forever.

WHAT DECIBO MEASURES • A / C / Z frequency weighting (IEC 61672 standard) • LAeq — equivalent continuous A-weighted sound level • Lmax — maximum during measurement period • LCpeak — C-weighted peak (instantaneous extremes) • TWA — 8-hour time-weighted average for OSHA / NIOSH • Dose — % of permissible daily noise exposure • Real-time 1/3-octave spectrum (30 bands, 25 Hz to 16 kHz) • Peak hold over a sliding 1-30 second window

REAL ZERO CALIBRATION Two methods: silent-room (3-second baseline auto-tunes to 30 dB SPL) and reference-tone (input your 94 dB SPL calibrator's measured value and Decibo computes the offset). Multiple named profiles per device, optional iCloud sync across your iPhones.

8 SCENE PRESETS — EACH WITH SMART THRESHOLD • Workplace — 85 dB / A-weighted / NIOSH dose tracking • Concert / Club — 100 dB / C-weighted / hearing-protection alert • Sleep / Baby Room — 50 dB / A-weighted / WHO bedroom guideline • Restaurant — 75 dB / A-weighted / chronic-exposure warning • Office — 65 dB / A-weighted / productivity zone • HVAC / Appliance — 40 dB / A-weighted / residential noise floor • Studio / Quiet — 35 dB / A-weighted / recording-grade silence Each preset comes with concise advice citing OSHA / NIOSH / WHO. Settings includes a custom-threshold override slider.

LIVE ACTIVITY, WIDGET, THRESHOLD ALARM Long sessions display current dB + LAeq + Dose in Dynamic Island and on the lock screen. Home + lock-screen widget for one-tap measurement. When sound crosses the active threshold, Decibo fires a haptic + optional notification — so you can step out, put in earplugs, or grab evidence.

SESSION HISTORY Every recorded session is saved with full time-series + metrics. Each session can be named and annotated. iCloud sync (opt-in) keeps history across your devices. Export as PDF (formatted report) or CSV (raw time series). Optionally geo-tag sessions for noise complaints or real-estate inspections.

BLUETOOTH-MIC PROTECTION If your hearing aids or AirPods are connected, iOS may route the iPhone microphone through them — yielding wrong readings. Decibo detects this and warns you with a red banner. One tap forces the built-in iPhone mic.

AUDIO FILE IMPORT Drop in any voice memo, recording, or .m4a / .wav / .mp3 — Decibo runs it through the same A/C/Z weighting + SPL pipeline and shows LAeq, Lmax, peak with a line chart.

100% ON-DEVICE The microphone audio never leaves your phone. No server. No cloud call. No third-party analytics. No tracking SDKs. AVAudioEngine captures, Accelerate processes, SwiftUI renders. The Privacy Nutrition Label says "Data Not Collected" — because it doesn't.

DISCLAIMER Decibo is a sound level meter for environmental and occupational measurement. It is not a medical device, not a substitute for a calibrated professional instrument, not for clinical hearing-loss diagnosis. For audiology concerns, consult a hearing-care professional.

MADE BY ONE PERSON An indie developer tired of decibel apps that charge $40/year and still can't zero properly. If something breaks or you want a feature, email xxhhuan2022@163.com — you'll get an actual reply, usually within a day.

https://duolaamengweb3.github.io/decibo/