dB Halo: Sound Meter

From a home workshop and HVAC rumble to a gym floor or concert venue, dB Halo helps you understand sound without sending data off your device. The large Halo safety ring shows live dB at a glance, with minimum, average, maximum, and peak readings plus a time-stamped event log. Choose A, C, or Z weighting, connect an external microphone, and save multiple calibration profiles for different setups. Analyze one live session in three synchronized views: FFT Spectrum, RTA octave bands, and Spectrogram. Noise Dose estimates daily exposure against NIOSH or OSHA criteria and shows remaining safer time. The on-device Sleep Journal recognizes and classifies snoring, breathing, speech, coughing, alarms, animal sounds, impacts, ambient sound, and crying, then logs each event without saving raw microphone audio. Microphone audio is not saved by default; an AAC file is created only when you explicitly start a recording. History keeps every saved session organized and ready to review. Export selected measurements as visual PDF reports or CSV data, export explicitly recorded AAC files, and burn dB overlays onto photos and videos. Export environmental audio levels to Apple Health, check Home and Lock Screen widgets, use App Intents and Shortcuts, and take standalone measurements on Apple Watch. There is no account, no ads, no analytics, and no tracking. Processing stays on your devices. Each general feature that produces a result includes three free uses. Spectrum, Noise Dose, and Sleep Journal each include one. A use counts only after a result is created; cancellations, permission denials, and failures do not count, and existing results remain readable. Lifetime Pro is one non-consumable in-app purchase: pay once, own it forever, with no subscription. Measurements are estimates. dB Halo is not a certified professional sound level meter and does not replace medical advice or an occupational safety determination. Optimized for iPhone Duo.