NoiseLedger: dB Meter & Log

NoiseLedger is a free decibel meter and noise log for Android. Measure sound levels in real time, record all night, and export a PDF report you can actually show someone — no ads, no account, no subscription, and no cloud.

MEASURE WITH CONFIDENCE
• Real-time dB with FAST or SLOW response, plus MIN / Leq / MAX
• A, C and Z frequency weighting
• Calibration wizard so you can match a reference sound level meter
• Honest clipping detection tells you when the microphone hits its limit

PRO NOISE METRICS, COMPLETELY FREE
• Noise dosimeter to NIOSH (85 dB, 3 dB exchange) and OSHA (90 dB, 5 dB)
• Live dose %, TWA, and a projection of when you reach the daily limit
• Percentiles L10 / L50 / L90 / L95 — L90 is your background noise, L10 the peaks
• Time above threshold and a full dB histogram

SEE THE SOUND
• FFT spectrum with a peak frequency readout
• Scrolling spectrogram (waterfall view)
• 31 third-octave bands with peak hold

RECORD IT AND PROVE IT
• Multi-page PDF report: chart, statistics, percentiles, dose, and a threshold-exceedance table with start, end, duration and maximum
• CSV and PNG export through the standard share sheet
• Overnight recording with adaptive sampling, an auto-stop timer and a quiet night preset
• Noise log history with search, date and dB filters, tags, notes and markers
• Multi-select for bulk CSV export or bulk delete
• Trends dashboard: daily Leq, streaks, your loudest day and hour
• Threshold alerts and QR preset sharing between devices

WHAT PEOPLE USE IT FOR
• Noise complaint evidence — run an overnight noise log and export a PDF showing exactly when the limit was exceeded
• Documenting neighbour noise, traffic noise or construction noise for a landlord, council or building manager
• Workplace noise checks with a free noise dosimeter and daily dose tracking
• Hearing protection — see how loud a concert, club, workshop or machine really is in dB
• Home and office sound level checks: is this room too loud to sleep, record or concentrate in?

A decibel meter tells you the sound level right now. A noise log proves what happened all night. NoiseLedger is both — a dB meter, a sound level meter and a noise recorder that turns measurements into evidence.

PRIVACY BY DESIGN
Audio is analysed live and is never recorded, stored or uploaded. No accounts, no analytics, no trackers, no cloud. Everything stays on your device and you can erase all data at any time from Settings. The app works fully offline.

ACCURACY NOTE
NoiseLedger uses your phone's built-in microphone, so readings are approximate and vary between devices — use the calibration wizard to improve them. This is a useful indicator, not a certified instrument. For legal, workplace-compliance or safety-critical measurements, use a calibrated Class 1 or Class 2 sound level meter.