Loudness-matched A/B for two masters

A louder version always sounds better for a second, and that's how revisions get approved for the wrong reason. Drop two files and hear them at the same loudness, so you judge the master and not the level. Measured in your browser, nothing uploaded.

A
Drop file A
WAV, FLAC, AIFF, MP3. Or click.
B
Drop file B
WAV, FLAC, AIFF, MP3. Or click.
Both files stay in your browser. Nothing is uploaded, nothing is stored, the audio is never altered.

Let your client A/B the same way, then sign off

Soneam turns this into a shareable review link. Your client compares versions level-matched with Fair Loudness, leaves feedback pinned to the waveform, and approves, with no account to create. Then deliver the master, password-protected.

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Why match loudness
Played back to back, the louder file wins on first impression even when the quieter one is the better master. Matching the level removes that bias, so the decision is about the music. Engineers gain-match plugins for the same reason.
Measured to the standard
Integrated loudness is computed with ITU-R BS.1770 K-weighting and gating, the same standard streaming platforms normalize to. The louder file is attenuated toward the quieter one, never boosted.
Nothing leaves your hands
Both files are decoded and played in your own browser. The match is level only, applied with the player's volume, so the audio stays bit-perfect. We never store files or train AI on them.

Fair Loudness FAQ

Why compare two masters at matched loudness?

A louder version sounds better for a few seconds, even when it isn't, and that bias is how revisions get approved for the wrong reason. Matching both files to the same loudness removes the level difference, so you judge the master and not the volume. It's the same reason mix engineers gain-match plugins before deciding whether one sounds better.

What does blind mode do?

Blind mode hides the file names and randomly swaps which button plays each file, so the on-screen position can't tell you which is which. You audition 1 and 2, pick the one you prefer, then reveal to see which file you chose and whether it was the louder one. It takes your own expectation out of the decision.

How is loudness measured in the browser?

Each file is decoded locally and its integrated loudness is measured with ITU-R BS.1770 K-weighting and gating, the same standard streaming platforms use. The measurement runs entirely in your browser; the file is never uploaded.

Does matching loudness change my audio?

No. The louder file is attenuated toward the quieter one using the player's volume only, so the audio data is untouched and bit-perfect. Nothing is boosted, re-encoded, or resampled; you hear the real master, just at a fair level for comparison.

What files can I compare?

WAV, FLAC, AIFF, MP3, and AAC, as long as your browser can decode them. For mastering comparisons use the lossless files (WAV or FLAC). Both files load from your own machine and play locally.

Is my file uploaded or stored?

No. Both files stay in your browser for measurement and playback. Nothing is sent to a server, nothing is stored, and we never use audio to train AI.

Related: free loudness meter & streaming preview · LUFS, true peak & dynamic range explained