THD Meter | SoundShockAudio

THD Meter is a MathAudio analysis plug-in for measuring total harmonic distortion in sound cards, speakers, and headphones. It generates a test tone, measures one channel at a time, and reports the result after a defined measurement interval, making it a focused utility for checking an audio chain rather than shaping a mix.

Matched filters help improve signal-to-noise performance when the measured system has additive noise. You can choose a test frequency from 20 Hz to 10 kHz, set the output channel and input source, and increase denoising when you need a longer, more precise measurement.

The plug-in accepts microphone calibration files in .frd, .cal, and .txt formats for speaker and headphone checks. MathAudio also supports sample rates from 44.1 kHz through 384 kHz without resampling, so the test can follow the highest rate supported by the audio interface.

This is best treated as a practical diagnostic tool: first establish the sound card’s own distortion with a line-out-to-line-in loopback, then use a microphone path to investigate speakers or headphones. The current release adds CLAP support alongside the established VST, VST3, and AU builds.