Measure noise like a pro — straight from your iPhone. Sound Level Meter: Decibel turns your iPhone into a precision SPL meter, engineered to the IEC 61672-1 international standard. Protect your hearing, document a noise complaint, tune a studio, or pre-check a workplace - reliable readings in seconds, clean A4 PDF reports in one tap. KEY FEATURES • Real-time dB readings with A, C and Z weighting — switch on the fly • Fast (125 ms), Slow (1 s) and Impulse time integration — the modes pros use • 1/3-octave frequency analysis • Multiple live visualizations: histogram, gauge, circle meter, applause meter, basic graph • All metrics in one place: LAeq, Min, Max, Avg, Peak • Save full measurement sessions with timeline, location and notes • Calibration screen for fine-tuning against any reference meter • Available in English, French, German, Spanish, Italian, Japanese, Chinese • Distraction-free dark interface focused entirely on your data DESIGNED FOR ACCURACY Sound Level Meter: Decibel follows the IEC 61672-1 sound level meter specification: • True biquad-cascade A and C weighting filters — not generic high/low-pass approximations • Exponential averaging on squared pressure (the correct method) • Per-device calibration based on the iPhone hardware actually in use • User-adjustable offset to align with any reference meter or calibrator IDEAL FOR • Audio engineers tuning studios, venues and rehearsal spaces • Workplace safety pre-checks before a formal acoustic survey • Musicians, DJs and podcasters watching their hearing exposure • Parents monitoring nursery or kids' bedroom noise levels • Tenants documenting noise from neighbors, traffic or construction • Anyone serious about long-term hearing health FAQ How accurate is it? After one-time calibration against a known reference, expect 2–3 dB of typical accuracy in the 40–95 dB range. Maximum measurable level is bounded by your iPhone hardware (around 104–110 dB). Does it replace a certified sound level meter? For monitoring, awareness and personal documentation: yes. For legally certified acoustic measurements, dedicated class 1/2 hardware remains the reference. Can I export my measurements? Every saved session generates an A4 PDF with full stats and the timeline graph. Print it, email it, AirDrop it — anywhere PDFs work. Why do I see different values than another decibel app? iPhone microphone sensitivity varies between models, and each app handles calibration differently. Use the built-in calibration screen to align with a trusted reference. How is my data handled? Sessions are stored locally on your iPhone. Nothing is uploaded — your acoustic data stays yours. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy: https://sonometredecibelmeter.blogspot.com