Sound Meter: Decibel & Noise

Sound Meter turns your phone into a decibel meter with NO time limit: real-time dB(A), min/avg/max and Leq, A/C/Z weighting, a level chart and a NIOSH/OSHA noise dosimeter. No account needed. Now in 12 languages.

Sound Meter is free with ads. Sound Meter Pro (subscription or one-time purchase) removes the ads and unlocks every Pro feature.

FREE — NO TIME CAP
✓ Needle gauge (30–120 dB) and big readout, green / amber / red zones
✓ Unlimited measuring time; min / average / max / Leq and L10 / L50 / L90
✓ A / C / Z weighting (IIR filters approximating IEC 61672); Fast, Slow, Impulse
✓ Pause and resume: paused time is left out of every number
✓ Keep measuring with the screen off, with the live level in a notification (up to 60 min free)
✓ Your last 3 measurements are saved, with chart, note and place
✓ Mark events and tag them: music, voices, footsteps, traffic, construction, dog, machine
✓ Loudest moment: replay the 10 seconds around the peak after you stop (optional audio clips)
✓ Night summary for sessions over 30 minutes: Leq in quiet hours, background, loud-event count, the 5 loudest events and the longest quiet stretch
✓ Colour-blind safe colours, thick chart line, full-width chart in landscape
✓ Widget, classroom noise light, room check, readings printed on a photo
✓ Manual and two-point calibration, external USB or wired microphone, raw input where supported
✓ Overload and noise-floor warnings, auto-stop timer, big flip display

ADS AND PRO, PLAINLY
• Free shows a banner and, at most every few minutes, a full-screen ad after you stop — never while you measure.
• Pro: monthly, 3-month or yearly subscription (yearly has a free trial for new subscribers) or a one-time lifetime purchase. Cancel any time in Google Play.
• Not ready to buy? Watch a short video to unlock every Pro feature for 30 minutes.

PRO FEATURES
★ Keep every session (free keeps the last 3; nothing is ever deleted), filter history by tag
★ A short audio clip at every threshold crossing, saved with the session and shown on its chart
★ Exclude a range (a passing motorbike) from a saved session: stats recompute from 1-second levels, noted in PDF and CSV
★ Night summary page in the PDF, with your own quiet hours
★ Pinch-zoom and pan over a whole saved session
★ CSV and PDF export with chart, tags, place and calibration
★ Octave spectrum 31.5 Hz–16 kHz; Leq per 1/5/15/60-minute interval; threshold-crossing log
★ Compare two saved sessions
★ Noise dosimeter — NIOSH REL and OSHA PEL side by side: dose % and 8-hour TWA
★ Threshold alert (40–110 dB) with vibration and red flash
★ Calibration profiles; unlimited screen-off measuring
★ No ads

PRIVACY
Sound is analysed on your phone; no recording, sample or measurement is uploaded. Short audio clips are saved only if you turn them on and never leave your phone; they are deleted with their session. Ads (Google AdMob, Unity Ads) may use your advertising ID; where the law requires it, you are asked first. Crash and anonymous usage reports can be switched off in Settings.

PERMISSIONS
Microphone, to measure the sound level. Notifications and a foreground service, only when you choose to keep measuring with the screen off, so Android shows the live level and a Stop button. Internet, for ads, purchases and crash reports. Vibration, only for the threshold alert.

Phone microphones are not certified instruments; readings are indicative (typically ±3 dB) and the night summary is for personal documentation, not a certified measurement. For legal or occupational compliance, use a calibrated Class 1/2 meter.

Recent changes:
• Start after 3, 5 or 10 seconds: a countdown before measuring so the tap on Start doesn’t end up in Leq or the maximum