Noise Level Meter - NM

NM is a noise level meter built on the real thing: the A and C weighting curves from IEC 61672, implemented as actual filters instead of a raw level with a dB(A) label stuck on top. MEASURE, DO NOT GLANCE A single number on a dial tells you almost nothing — a room swings by 20 dB while you are looking at it. NM runs a measurement instead. Press start, let it run a minute or ten, and it hands you a record with the Leq (the energy average of the whole run), the peak, the minimum, L10, L90 and a chart you can read afterwards. WEIGHTING THAT IS ACTUALLY WEIGHTING • A-weighted — follows human hearing. Noise limits and hearing-safety figures are written in this weighting. • C-weighted — nearly flat in the bass. For peaks and low-frequency rumble. • Z — no weighting at all, the level as the microphone heard it. Each curve is a cascade of biquad filters normalized at 1 kHz, so the response matches the published table rather than an approximation of it. EXPOSURE, NOT JUST LOUDNESS 85 dB(A) is safe for eight hours, and every 3 dB above that halves the safe time. NM shows the NIOSH exposure clock for the level you are standing in, so you can tell a room that is merely tiring from one that is doing damage. MEASUREMENT MODE, FORCED iOS runs automatic gain control by default, which quietly rewrites the reading while you watch it. NM forces the audio session into measurement mode, which switches that off. Without it, no meter on a phone means anything. HONEST ABOUT THE LIMITS A phone is not a class 1 or class 2 sound level meter, and NM has a whole screen that says so: • Its microphone compresses and clips around 100–110 dB, so at a concert or beside machinery it reads LOW, not high. • Below roughly 30 dB it is measuring its own hiss, so NM stops giving a number it cannot stand behind. • Every handset differs, so the absolute figure is an estimate until you set the calibration offset against a real meter. Never use NM for legal, occupational or compliance measurements. IT NEVER RECORDS NM reads the level out of each audio buffer and throws the samples away. No audio is recorded, kept or sent anywhere. Measurements and settings live on this device, and there is no account. FREE • Live A-weighted level with the exposure ladder • Full measurements with Leq, peak, L10 and L90 • Your three most recent measurements kept PRO • C and Z weighting as well as A • Every measurement kept, and exported as CSV • Calibration offset against a real sound level meter • The screen stays awake through a whole measurement SUBSCRIPTION NM Pro is offered as a weekly subscription with a 3-day free trial, or as a yearly subscription. Payment is charged to your Apple Account at confirmation of purchase. A subscription renews automatically unless you turn off auto-renew at least 24 hours before the end of the current period. Manage or cancel in your Apple Account settings at any time. Any unused portion of a free trial is forfeited when you buy a subscription. Privacy Policy: https://leomarston.github.io/manycode-legal/privacy.html Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/