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THD - Total Harmonic Distortion - Test Tones


Total Harmonic Distortion (THD) characterizes the linearity of an audio device and is a good indication of the distortion present at its output. Assuming you feed the device with a pure tone, THD will represent its deviation from its pure form. The lower the THD, the better! Standard THD tests use a 1kHz sine tone, and so does this page. To discuss the use of other frequencies, check out our extended THD test set.

Per definition, a sine tone has no THD. It is commonly accepted that THD measurements below 1% are inaudible. With this series of test files, you can judge for yourself if it's true.


You can use these test files to determine how much distortion you can hear or to calibrate a THD measurement device using the .wav files version (patrons only).

The sound files

0% 0.001% 0.005%
0.01% 0.05% 0.1%
0.5% 1% 5%

Each file plays a 1kHz sine tone (5s) at -6dBFS with increasing THD levels.

Start with the pure tone (O%) and then increase the THD until the tone coloration/distortion becomes audible to you.

Beware, your equipment's own THD will corrupt this listening test! You will not be able to discriminate THD figures lower than what your own audio equipment gives you access to.

If your headphones suffer from a 0.1% THD (e.g. the Sennheiser HD-600 reference headphones), a pure sine tone (0% THD) will reach your ears with 0.1% distortion. You won't be able to discriminate THDs lower than 0.1% under these conditions.

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