Audio & signal processing, explained with the tools next to the theory
Every article on this site walks through the maths behind a measurement, the engineering traps that come with it, and then hands you a calculator that does the work in your browser. Nothing is uploaded, nothing is stored, no account is needed.
Core articles & embedded tools
Each entry below is a full tutorial page with a working tool built into the body of the text — not a bare calculator page. Publication order follows the schedule in the article index.
-
Published
dB Conversion: dBFS, dBu, dBV, dBm and dB SPL
dBFS, dBu, dBV, dBSPL and dBm converted in both directions, with an explanation of every reference level and why dBV and dBu are not interchangeable.
-
Published
IEEE 754 Float ↔ Hex, Decoded Field by Field
Single and double precision bit patterns, subnormals, ULP, and how to read a capture from a logic analyser without guessing.
-
Published
Window Functions: Leakage, Resolution and Sidelobes
Hann, Hamming, Blackman, Nuttall and flat-top: coefficients, coherent gain, ENBW, main lobe width and sidelobe levels, with a live magnitude response.
-
Published
FFT Spectrum Analyser: Peak, RMS and Scalloping Loss
Generate a signal or load a capture, then compare the tallest bin with the interpolated peak, the time-domain RMS, the noise floor and the noise density.
-
Published
Dual-Channel Coherence: Averages, Bias and Thresholds
Magnitude-squared coherence with Welch averaging, the 1/K bias, the 95% significance threshold, and why a pure delay leaves coherence at 1.
-
Published
FIR Design by Windowed Sinc: Taps, Transition and Attenuation
Low-pass, high-pass, band-pass and band-stop coefficients, with the measured trade-off between tap count, transition width, stopband attenuation and group delay.
Extended series
Follow-ups that take one subject further, where the practical question turns out to be subtler than the theory.
-
Published
THD, THD+N, SINAD and ENOB
Measure distortion from a captured tone, with the definitions, the bandwidth caveat, and the harmonic arithmetic people get wrong.
-
Published
Biquad Coefficients (RBJ Cookbook)
Peaking, shelving, low-pass, high-pass, band-pass, notch and all-pass coefficients with the response and group delay measured from them.
-
Published
Speaker SPL & Amplifier Power
Sensitivity in either convention, level against distance, air absorption, cabinet stacking and the power a target level really needs.
-
Published
Level Summation Calculator
Add correlated and uncorrelated levels, stack identical sources, remove a noise floor, and average levels over time.
-
Published
Loudness & True Peak Analyser
Integrated LUFS with the gating shown block by block, loudness range, and true peak against the sample peak.
-
Published
Room Mode Calculator
Mode spectrum with coincidences flagged, mode count against the asymptotic curve, and the pressure shape of any mode.
Supporting calculators
Smaller utilities that cover the checks you make in passing: CRCs, sampling limits and acoustic timing.
-
Published
CRC-8/16/32 Calculator
All the standard parameter sets with their catalogue check values, plus custom polynomial, init, reflection and final XOR.
-
Published
Nyquist & Aliasing Calculator
Where an out-of-band tone folds to, the samples per cycle, what oversampling is worth, and the jitter-limited SNR.
-
Published
Acoustic Time & Distance Calculator
Delay, distance and temperature-dependent speed of sound, with the sensitivity that decides whether the answer matters.
How these tools are built
All arithmetic runs client-side in JavaScript, with the numerically heavy parts (FFT, coherence, RMS accumulation) moving to WebAssembly as the site grows. That choice is deliberate: your measurements never leave the machine, and the page keeps working offline once loaded.
Results are shown with significant digits chosen for the magnitude involved, because pasting a raw double into a report is how rounding errors get published. Where a quantity is only valid under a stated assumption — a reference level, a window, an averaging count — the article says so and the tool says so.
This site is supported by advertising. Ad vendors set their own cookies, which is described in the privacy policy; the tools themselves collect nothing.