Decibly: Decibel & Sound Meter

Decibly is a sound meter and decibel meter that shows the noise level around you in dB, live, using your phone's microphone.

Why Decibly
No ad will interrupt a measurement: there is a small banner on the measuring and history screens, and a full-screen ad can only appear after you close a saved session, never while you are measuring. The numbers are honest, too. The unit is always on screen (dB(A), dB(C) or dB(Z)), and when the microphone reaches its limit the reading shows "≥" instead of quietly cutting off. Every measurement feature works without paying.

What you get
• Real-time sound level in dB with A, C or Z frequency weighting and Fast (125 ms) or Slow (1 s) time response
• Circular gauge with colored zones (quiet, moderate, loud, harmful) and a big number; respects the system "remove animations" setting
• Live 60-second graph with your alert threshold line
• Min, Leq (energy average), Max and Peak
• Noise exposure with A-weighting: NIOSH noise dose %, 8-hour TWA and recommended allowed time (reference only, NIOSH 85 dB(A) / 8 h / 3 dB exchange rate)
• Noise guide with approximate everyday examples, from a whisper (30 dB) to a siren (120 dB), the NIOSH table and a WHO safe listening note
• Noise alert: vibration and an on-screen flash above a threshold you set (works while the app is on screen)
• Calibration: compare with a reference sound level meter and compute an offset from a 3-second average, or adjust in ±0.5 / ±1 dB steps (range ±30 dB). Saved per device model and applied exactly once
• Microphone overload indicator: "≥" on the number, and Max/Peak keep the mark
• Uses the unprocessed microphone source when your phone supports it, otherwise the voice-recognition source, without automatic gain. The source in use is shown in settings
• Save sessions with a name and a note, browse your history, and open a session graph with pinch zoom
• CSV export: share it or save it to a file (dot decimals, ISO timestamps)
• Keep the screen on while measuring, auto start, light and dark theme
• Available in 32 languages

Privacy
Audio is never recorded or saved. Decibly only calculates sound levels in memory. The microphone is used only while you are measuring with the app on screen; there is no background measuring.

Ads and purchase
A one-time purchase removes ads. There is no subscription.

Good to know
• A phone microphone is not a Class 1/2 sound level meter. Readings may differ by several to over 10 dB between devices. Do not use it for legal or medical measurements.
• For readings closer to a reference meter, use the calibration screen with a real sound level meter under the same conditions.
• Exposure figures (dose, TWA, allowed time) are for reference only and appear only with A-weighting.
• Alerts work only while Decibly is open on screen.