Overtone Lab: Acoustics & RT60

Overtone Lab is a precision calculation studio for musicians, instrument builders and audio engineers — 26 exact tools in one offline app, in seven sections. TUNING • Partch — just intonation, cents, nearest just ratio, Tenney height • Comma — equal divisions (EDO) & historical temperaments • Mersenne — string tension, frequency & fret spacing TIMING • Tempo — note & bar lengths, time↔samples, varispeed • Delay — tempo-synced delay, distance alignment, comb filtering • Timecode — SMPTE 24 / 25 / 30 & 29.97 drop-frame • Pitch — note↔frequency↔wavelength, harmonics, beats, Doppler ACOUSTICS • Sabine — room reverberation (RT60), Schroeder frequency, room modes • Webster — exponential horn cutoff & Helmholtz resonance • Bernoulli — open/closed pipe resonance & end correction • Formant — vocal-tract formants & vowel presets • SPL — inverse-square distance law & source summation • Room Modes — axial/tangential/oblique modes, Bonello & Sepmeyer ratios • Air — atmospheric absorption & speed of sound (ISO 9613-1) • SBIR — speaker-boundary interference & comb filtering SIGNAL • Butterworth — filter response & Linkwitz-Riley crossovers • Fletcher — A / C / Z frequency weighting • Benchmark — real ITU-R BS.1770 integrated loudness (LUFS) & streaming targets • Passive — RC / RL / LC filter corners • Biquad — digital IIR filter coefficients (RBJ cookbook) • Compressor — gain computer, soft knee & attack/release time constants STEREO • SRA — stereo recording angle for mic arrays (ORTF, NOS, DIN, Blumlein) UTILITY • Levels — decibels, dBu / dBV, dynamic range • File — uncompressed size, sample rate & Nyquist frequency • Pan — equal-power & linear pan law DESIGN • Thiele — Thiele-Small sealed & ported loudspeaker enclosures Every result is computed from published formulas and validated against reference sources. Type any value and the whole screen recomputes instantly. 100% offline — no account, no network, no tracking, no subscription. Buy once, use forever. Universal for iPhone, iPad and Mac. Estimates for design and study; cross-check critical work against measurement.