Decibly - Sound Meter

TecDroid Developer

About this app

Decibly measures how loud it is, keeps a noise log for hours, even overnight with the screen off, and turns it into a report with times, events and the method used. Every number is labelled as measured or estimated, and nothing you measure leaves your phone unless you share it.

HOW LOUD IS IT
• A dial that breathes with the room: the sound level in dB (an estimate from the phone's microphone) next to the exact digital level in dBFS
• Switch weighting between A, C and Z, and response between Fast, Slow and Impulse, with one tap
• Running Leq with Min, Max and Peak, and the L10, L50 and L90 percentiles
• A pulse strip of the last minutes with your threshold line and pins on the loudest moments
• Everyday sounds beside the dial, so a number means something (values from a public health source)
• Stage mode: one large number to read from across the room
• A warning when a sound is louder than your phone's microphone can read

KEEP A NOISE LOG
• Screen on, background, or night watch: arm it before bed and it records only inside the time window you choose
• Background logging shows a notification with the live level and a Stop button, and never starts on its own
• Events above your threshold, the loudest moments, your notes and a place name you type (no location access)
• Noise exposure estimate with the NIOSH and OSHA formulas: dose, time-weighted average and a projected 8-hour value
• Stop after a set time or when the battery runs low
• Optional event clips: about 10 seconds of sound around each event, off by default, kept only on your phone

REPORTS YOU CAN SHARE
• PDF report (A4 or Letter) with the level chart, events, exposure estimate, octave levels, the method and an accuracy statement
• CSV and JSON export of the 1-second levels
• Sessions grouped by day, with search and filters, a zoomable chart, rename, notes, and delete with undo
• Compare two sessions on one chart
• Spots: name a spot, measure it for 15 seconds and compare rooms side by side

SEE THE SOUND
• Spectrum with peak frequency and the nearest musical note, as a line or in 1/3-octave bands
• Waterfall that scrolls in real time: pinch for the time span, tap for a crosshair, double-tap to freeze
• Tone finder that picks out steady hums and whines, including 50 or 60 Hz mains hum, and lights them in the waterfall

YOUR MICROPHONE, YOUR CALIBRATION
• Calibration profiles for the built-in microphone and for a headset or USB microphone that Android routes to the app
• Calibrate against a reference sound level meter or a 94 dB calibrator, or type an offset
• Mic check: the quietest level your phone can read and where it starts to clip
• "How accurate is a phone?": a plain explainer with its sources

ON YOUR HOME SCREEN
• Last session widget and a live logging widget
• Quick Settings tile and app shortcuts for the meter, a new session and your reports
• Share a reading as an image card with the weighting and the "estimate" label

HONEST NUMBERS
Phone microphones are built for speech. Without calibration a reading can be several decibels off, and very loud sounds may read low. Decibly shows which values are estimates, puts the method in every report and does not replace a calibrated sound level meter. The exposure figure is an estimate from your phone, not a medical measurement.

PRIVACY
Sound is turned into numbers in memory and never uploaded. The only audio Decibly can keep is an optional event clip, stored in the app's private storage on your phone; you can play and delete clips at any time. No account and no location. Crash reports and basic usage statistics (Google Firebase) help fix problems; see the privacy policy.

PERMISSIONS
• Microphone: to measure sound levels, only while a meter is on screen or a session you started is running
• Notifications: to show background logging and its Stop button

In 18 languages.

Questions or ideas: [e-mail]

What’s new

First release of Decibly:
• Sound meter with A, C and Z weighting, a living dial and Leq, L10, L50, L90
• Noise log with the screen on, in the background or overnight (night watch)
• Events, notes and a noise exposure estimate (NIOSH and OSHA formulas)
• PDF, CSV and JSON reports; spots and session compare
• Spectrum, waterfall and tone finder
• Calibration profiles and a mic check
• Widgets, Quick Settings tile and shortcuts