Measured 22 September 2026
What we measured
Restoration results on a public-domain recording, with the method written out so you can run it yourself. Two of the four results argue against us and are here for the same reason the others are.
Restoration is the one capability that needs no human to compare against. Take a clean file, inflict a defect you control, repair it, and measure how far the result sits from the original. The right answer is exact, so the test is falsifiable rather than a matter of taste.
The second number is the one an engineer actually asks for. The same chain is run on undamaged audio, to measure what it does to a file that was already fine. A denoiser that recovers 8 dB and takes 3 dB out of a clean take is not a denoiser worth having, and only measuring both reveals it.
- Source
- Chopin, Mazurka Op. 7 no. 4 — Musopen, released under CC0 1.0, via the Internet Archive. Public domain recording of a public-domain composition, so both rights are clear and you may use the same file.
- Excerpt
- 22 seconds, 44.1 kHz stereo, set to 0.7 peak for headroom.
- Harness
- The same defect functions and signal-to-error metric the engine is held to in its own quality suite, pointed at a file whose licence can be stated.
| Stage | Recovery | Removed that was music | Effect on clean audio |
|---|---|---|---|
| Hum removal | +10.31 dB | 0.0% | −111.1 dB |
| Click repair | +7.70 dB | 0.0% | −48.1 dB |
| Noise reduction | +1.86 dB | 2.9% | −40.3 dB |
| Declipping | +0.50 dB | 15.9% | −49.9 dB |
Recovery above zero means the repair removed more than it added. The last column is how far the chain moves audio that had nothing wrong with it — more negative is better, and −111 dB is silence.
Hum removal
Click repair
Noise reduction
Declipping
Nothing here compares Euphona to a human engineer. Every figure is a distance from a known-clean file, not a judgement against someone’s work, and we do not publish a parity or superiority claim because we have not run the listening panels that would support one.
Nor is one recording a general result. These numbers describe solo piano at 44.1 kHz with defects we injected. Different material moves them — declipping in particular is close to its worst case here, because piano reaches the rails for only a few hundred samples.
- 01
Take the same file
Download the Musopen Chopin collection from the Internet Archive. It is CC0, so nothing about re-using it is in question.
- 02
Break it in a way you control
Add hum, clicks, hiss or clipping to a copy. Keep the original — it is the reference that makes the answer exact.
- 03
Repair it
Run the damaged copy through restoration. The free tier gives ten minutes of the full engine and needs no card.
- 04
Null the result
Subtract the repair from the damaged file. What is left is exactly what was removed — listen for music in it, which is the test that matters.