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, AAC. Or click.
B
Drop file B
WAV, FLAC, AIFF, MP3, AAC. 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.

Start free
Why match loudness
Engineers gain-match before comparing plugins or EQ settings for a reason: at different levels you are listening to the level, not to what the processing did. This is that same step, applied to two finished masters instead of two settings.
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. Nothing is uploaded, so there is nothing here to store.

Free, and no account needed. Soneam is the other half: you send a client a link, they hear the master correctly, and they approve. What Soneam does.

Fair Loudness FAQ

Why compare two masters at matched loudness?

The ear reaches for level before it reaches for anything else, and first impressions are decided in the seconds where that pull is strongest. It is not a lapse in judgment; it happens to everyone, which is why a revision that only got louder can read as a revision that got better. Matched playback removes the difference, and what is left to hear is the work.

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, so there is nothing on our side to store.

Related: why louder sounds better, and how to A/B fairly · free loudness meter & streaming preview · LUFS, true peak & dynamic range explained