The readout
A single number, measured in real time, smoothed enough to actually read. The screen shifts colour with the level — green when quiet, amber at conversation, red when loud — so you feel the room before you read the value.
An ambient sound-level meter
DECIBEL
A precise, restrained instrument for understanding the room you're in. Real-time levels, calibrated to your phone, on-device only — no audio is ever recorded.
The interface
What it does
The recording
Tap once to start a measurement session. Decibel tracks peak and average levels along with a live waveform of computed levels. Tap again to stop, and the session is saved to your local history with its timestamp, duration, peak, and average — no audio, only the summary.
The instrument
Two-tier smoothing — a fast filter drives the bar and the background tint, a slower one keeps the headline number stable. Calibrate against a reference meter you trust to fine-tune readings for your specific iPhone. Custom typography, dark-only design, full-screen meter, no distractions.
On-device, always
Your audio never leaves your device.
- Audio is processed in real time and immediately discarded
- No audio is recorded, stored, or transmitted
- No analytics, no tracking, no accounts, no advertising
- No third-party SDKs, no network requests of any kind
On accuracy
iPhone microphones are not laboratory-calibrated, so the values shown are estimates. Treat them as a relative measure — how loud one environment is compared to another — not as certified sound-pressure measurements. Decibel is not suitable for hearing-safety decisions, OSHA / NIOSH compliance, or medical assessment. For those, use a certified Type 1 or Type 2 sound-level meter.