A real sound-level meter, not a "decibel-meter app"
Most "decibel meter" apps are dressed-up amplitude bars with no calibration. Decibel is a real sound-pressure-level meter — A, C and Z weighted; LAeq, LAmax, LCpeak; statistical Ln (L10 / L50 / L90); OSHA 8-hour dose accumulator; permissible-exposure-time calculator. Per-iPhone-model offset corrections so readings track an actual SLM within ±2 dB across the 60–100 dB range.
Wear an Apple Watch on a job site, in a club, or in a stadium and watch the live SPL on your wrist. Cross 90 dB and the wrist buzzes. End the day with a PDF noise-exposure report you can hand to HR, your doctor, or a workers'-comp lawyer.
No microphone audio leaves the device. Ever. The DSP runs in milliseconds in Apple's Accelerate framework. No subscription "fleet platform," no ads, no analytics, no accounts.
IEC 61672 weighting
A, C and Z frequency weighting. LAeq, LAmax and LCpeak — the full SLM toolkit.
OSHA & NIOSH dose
8-hour dose accumulator with permissible-time timer. PDF report exportable.
Apple Watch live meter
Glance at your wrist on a job site or in a club. Threshold haptic at user-configurable dB.
Per-model calibration
Per-iPhone offset table targeting ±2 dB across 60–100 dB. Pro+: manual ±5 dB trim.
Statistical Ln
Continuous L10 / L50 / L90 percentiles, useful for community-noise complaints.
100% on-device
vDSP-based, deterministic, < 5 % CPU. No cloud, no servers, no tracking SDKs.
Who Decibel is for
- OSHA-aware blue-collar workers — construction, manufacturing, oil & gas. Document your daily exposure across an 8-hour shift.
- Live-sound engineers, DJs, musicians — hearing protection is career insurance. Pre-flight a venue, watch LCpeak between songs.
- Parents — quantify the noise in a kid's bedroom or a daycare nap room.
- Older adults with mild hearing loss — quantitative awareness of restaurants, cafes and meeting rooms.
Subscriptions
Free to download. The free A-weighted meter is fully functional by itself — you don't have to subscribe to use it.
- Free: live LAeq (A-weighting), large-digit display, 7-day measurement history.
- Pro ($3.99 / mo or $24.99 / yr · 7-day free trial): C/Z weighting, LAmax/LCpeak, Ln percentiles, OSHA & NIOSH dose, Apple Watch live meter, PDF reports, unlimited history.
- Pro+ ($9.99 / mo or $59.99 / yr · 14-day free trial): everything in Pro, plus manual ±5 dB calibration trim and per-microphone profiles for acoustics pros.
Subscriptions are billed by Apple under your Apple ID. Cancel anytime in iOS Settings → Apple ID → Subscriptions.
Calibration disclaimer
iPhone and Apple Watch microphones are not Class 1 or Class 2 certified hardware. Decibel readings are intended for personal awareness, hearing-protection screening, and informal documentation. They are not suitable as legal regulatory evidence (e.g. an OSHA citation). For legal compliance, use a certified Class 2 or Class 1 sound level meter calibrated by an accredited lab.