Learn · acoustic science & testing guides

Authoritative, mathematically verified guides on sound reproduction, human hearing biology, signal synthesis, calibration methodologies, and digital audio DSP. Every guide directly connects to our browser-native testing instruments.

Tuning & Perception

7 min read·Instrument & Pitch Tuning Generator
432 Hz vs. 440 Hz Pitch Controversy: Acoustic Science, History, and PsychoacousticsSeparate acoustic facts from internet mythology: the historical evolution of concert pitch, ISO 16 standardization, Verdi tuning, and double-blind listening tests.

Signal Generation & Calibration

7 min read·Noise Generator (All Colors)
The Colors of Noise Explained: White, Pink, Brown, Blue, and Violet SpectraExplore the acoustic physics and power spectral densities (PSD) of noise colors: 0 dB, -3 dB, -6 dB, +3 dB, and +6 dB per octave slopes and calibration uses.

Digital Signal Processing

8 min read·Dithering and Noise Shaping Explainer
Dithering and Noise Shaping in Digital Audio: Eliminating Quantization DistortionUnderstand digital audio resolution: bit depth, quantization error, why adding random noise eliminates harmonic distortion, and psychoacoustic noise shaping curves.

Hearing & Psychoacoustics

7 min read·Hearing Test (Audiogram)
Normal Human Hearing Range: Frequencies, Limits, and Age-Related LossExplore the 20 Hz to 20,000 Hz human auditory spectrum, equal-loudness Fletcher-Munson curves, presbycusis aging patterns, and safe exposure guidelines.

Equipment & Calibration

Signal Generation & DSP

7 min read·Tone Generator
Audio Waveforms Explained: Sine, Square, Triangle, and Sawtooth HarmonicsDiscover the harmonic anatomy of synthesis waveforms: Fourier theorem, odd vs even harmonics, phase relationships, and timbre perception.

Audio Measurement

7 min read·THD Audio Distortion Test
Understanding Total Harmonic Distortion (THD): Measurement, Linearity, and Audible ThresholdsMaster audio fidelity metrics: how Total Harmonic Distortion (THD) and THD+N are calculated, even vs odd order harmonics, and real-world audibility limits.

Critical Listening & Testing

8 min read·ABX Double-Blind Testing Suite
Understanding ABX Double-Blind Audio Testing: Methodology, P-Values, and Statistical SignificanceHow double-blind ABX perceptual audio tests eliminate cognitive bias, calculate cumulative binomial p-values, and prove whether audible differences truly exist.

Acoustics & Physics

6 min read·Subwoofer & Low Frequency Test
Why Smartphones Physically Cannot Reproduce 20 Hz: The Acoustic Limits of Micro-TransducersA deep dive into acoustic physics: Hoffmann's Iron Law, volume displacement, acoustic short-circuiting, and why phone speakers cannot produce true sub-bass.