SoundMess Lab: SPL Meter

SoundMess Lab is a careful, offline sound measurement tool for iPhone and iPad. Built for musicians, producers, podcasters, acoustic enthusiasts, and anyone who wants to understand what they're hearing. WHAT IT MEASURES • SPL meter — A/C/Z weighting, Fast/Slow/Impulse time weighting, Leq, L10, L90, Lmax, Lmin, Lpeak, with one-tap session reset • Real-time analyser — 1/1 to 1/24 octave bands with peak hold • FFT — Hann, Hamming, Blackman, Blackman-Harris windows, sizes up to 65,536, exponential averaging • Spectrogram — five tuned colour palettes, live and rolling (Pro) • RT60 — per-octave-band reverberation time, ISO 3382-2 T20 method with interrupted pink noise (Pro) • Signal generator — sine, pink, white, swept sine (Pro) • Reference-tone calibration — trim every reading against a known 94 dB source (Pro) BUILT CAREFULLY SoundMess Lab implements the IEC 61672 A/C/Z weighting curves with published coefficients to 10 decimals, Paul Kellett pink noise, and ISO 3382-2 T20 linear regression for RT60 fitting. Every reading shows a confidence indicator so you know which frequencies you can trust — built-in iPhone microphones have known hardware limits below 500 Hz and above 8 kHz, and we don't pretend otherwise. HONEST ABOUT LIMITS Every phone microphone has physical constraints. SoundMess Lab shows you where it can be trusted and where it can't. It's a serious listening tool for creative work — not a replacement for a calibrated measurement microphone in professional field acoustics or compliance settings. PRIVACY BY DESIGN Nothing you measure ever leaves your device. No account, no analytics, no ads, no cloud. Audio is only written to disk when you start a recording, and those files stay in your app sandbox until you choose to share them. FREE INCLUDES SPL meter (with L10 / L90 / session reset), 1/3-octave RTA, FFT (4096 · Hann), per-device microphone compensation, five themes. PRO UNLOCKS Spectrogram (live + rolling), RT60 room-acoustics measurement, fractional RTA (1/6, 1/12, 1/24), advanced FFT (sizes up to 65,536, Hamming / Blackman / Blackman-Harris windows, exponential averaging), signal generator (sine / pink / white / sweep), recording & playback, WAV / CSV / PDF export, reference-tone calibration, external mic calibration-curve import (.txt / .frd). PRICING • $8.99 one-time Lifetime · Family Sharing supported One-time purchase. No subscription, no auto-renew. BUILT FOR THE WORK Most sound apps optimise for the spike — big colourful needles and "how loud is a rock concert" trivia. SoundMess Lab is built for the work: reading a room, shaping a mix, checking a speaker, measuring a decay, teaching acoustics. Careful DSP, calm UI, no noise.