Distortion Test – THD & Intermodulation Listening Test
THD and IMDHarmonic distortion (pure sines)
Intermodulation (dual tones)
Ready
Two loud high tones can create a low “difference tone” in your own ear.
- Start quiet, raise slowly
- Check L/R markings first
- Disable audio enhancements
- Runs inside your browser
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Online THD and IMD distortion listening test
Clean audio reproduces a pure tone as a pure tone. These signals make added harmonics and difference tones audible so you can spot a clipping amplifier or a straining speaker.
Total harmonic distortion (THD)
THD is the power of added harmonics relative to the original tone.
Extended THD test set
Testing several frequencies matters because distortion varies across the range.
Intermodulation distortion (IMD)
When two tones pass through a nonlinear system, new tones appear at their sum and difference.
How to Use the
Distortion Test
- 01
Level
start with the volume low and the level slider at −6 dBFS.
- 02
Sines
play each tone; a pure sine is smooth and dull. Buzz, rasp or extra pitches mean distortion.
- 03
IMD
play the dual tones; a faint low tone that is not in the signal indicates intermodulation.
- 04
Push
raise the level step by step and note when the sound turns harsh.
Total harmonic distortion (THD)
THD is the power of added harmonics relative to the original tone. Amplifiers usually stay below 0.1 %, while speakers can reach several percent in the bass. Low sines are the most revealing because the harmonics fall where the ear is more sensitive.
Intermodulation distortion (IMD)
When two tones pass through a nonlinear system, new tones appear at their sum and difference. Hearing a 1 kHz whistle from the 19 + 20 kHz pair means something in the chain, often a small speaker or cheap DAC, is nonlinear.
Hearing and distortion
The logarithmic scale
Both pitch and loudness are heard logarithmically, which is why decibels and octaves are used.
Sensitivity varies with level
At low volume we hear bass and treble less; distortion is easier to judge at moderate level.
Check your hearing too
If tones sound rough on every device, test your hearing as well.
Related guides and fixes
Learn more in these guides: No sound on Windows, No sound on Mac, Headphones only one side, Speakers crackling, How to test speakers, How to test headphones.
Extended THD test set
Testing several frequencies matters because distortion varies across the range. Run through 50 Hz to 3 kHz at the same volume and note which tones sound rough.
Non-linearities of the ear
Your inner ear also creates combination tones at high levels. That is why the ear test plays an audible pair: at moderate volume many people hear a faint 400 Hz tone that is not in the signal.
Frequently Asked Questions
Q.Does distortion always mean my gear is broken?
No. Any speaker distorts at high level and low frequency. It matters when it appears at normal volume.
Q.Can I measure THD with this page?
Only by ear. A measurement needs a calibrated microphone or loopback and analysis software.
Q.Why are the 19 + 20 kHz tones silent?
That is normal. You only hear something if distortion produces a lower difference tone.