Audio A/B Test: Compare Two Audio Files Online
This free audio A/B test plays two audio files in sync and lets you flip between them with one big button, so you can compare two audio files online and hear exactly what differs. Nothing is uploaded. Both files are decoded and played inside your browser, with no account and nothing to install.
How to A/B test two audio files
- Tap Track A and choose your first file, then tap Track B and choose the second. Each can be a WAV, MP3, FLAC, AAC, M4A, OGG or Opus file up to 100 MB.
- When both files have loaded, the player appears. Press play and drag the timeline to a passage you know well.
- Tap the big A/B button to switch. The sound changes at once and the music carries on from the same moment, with no pause or restart.
- Use Change files to load a new pair.
Both tracks run together the whole time and the button only decides which one you hear. That is why the switch never skips or loses its place.
What an audio A/B test tells you
Switching back and forth on the same moment is the quickest way to hear a small difference, and it takes memory and mood out of the comparison. Musicians use an A/B test to check a new mix against the old one, to try a master against the reference track, or to see whether a change to a setting made things better or only different.
Compare audio quality: MP3 vs FLAC, mixes and masters
To compare formats, load the lossless original as one track and the compressed copy as the other. Listen for dull or fizzy high frequencies, a smeared stereo image and a thinner low end, and switch several times on a dense passage. Tip: do not look at which track is which. Ask a friend to load them in a random order, then see whether you can still tell them apart.
This is a straight A/B comparison, not a double-blind ABX test, so what you expect to hear can still colour what you hear.
Tips for a fair audio A/B test
- Match loudness first. This tool does not change the level of either file, and a louder track nearly always sounds better.
- Use the same moment. Loop your attention on a short passage and switch every few seconds.
- Use good headphones or speakers. Laptop speakers hide most of the differences you are testing for.
- Keep the volume fixed while you switch.
Fix tracks that are out of sync (sync offset)
If the two files do not start at the same point, the switch will jump. Open Advanced and move the sync offset slider. Positive values play Track B later and negative values play it earlier, up to 5,000 milliseconds either way. The small buttons move it 10 or 100 milliseconds at a time, and Reset puts it back to zero. A sharp sound such as a snare hit makes the right setting easy to hear.
Frequently asked questions
What is an audio A/B test?
An audio A/B test plays two versions of the same audio and lets you switch between them while the music keeps going, so you can hear what changed. You can compare two mixes, two masters, or the same song in two formats. Switching without a gap is what makes small differences easy to hear.
How do I compare the quality of two audio files?
Load one file as Track A and the other as Track B, press play, then tap the big A/B button back and forth on a part you know well. Because the playhead never moves, you hear the same moment in both. Short, repeated switches on one passage work better than listening to each file in full.
Can I compare two audio files online for free?
Yes. It is free, there is no account and nothing to install. Both files are decoded and played in your browser, so they are never uploaded. Each file can be up to 100 MB.
Is MP3 vs FLAC audible in an A/B test?
It depends on the bitrate, the music, your headphones and your ears. A high-bitrate MP3 is hard to tell from FLAC for most people, while a low-bitrate one often shows up as dull highs or a smeared sound. Load both versions and switch on a busy passage to find out for yourself.
Why do the two tracks need the same loudness?
Louder usually sounds better, even when it is not, so a louder track can win an A/B test by volume alone. This tool does not level-match the two files for you. Match their loudness in your editor before loading them if you want a fair result.
How do I sync two audio files that don't line up?
Open Advanced and move the sync offset until the two tracks line up. It shifts Track B later or earlier by up to 5,000 milliseconds, and the -10 and +10 buttons nudge it in small steps. Listen to a sharp sound such as a drum hit and adjust until switching no longer jumps.
Are my audio files uploaded anywhere?
No. The files are read and decoded in your browser tab and stay in your device's memory while you listen. Nothing is sent to a server, and closing the tab discards them.
Recommended
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Audio-Technica ATH-M20x studio headphonesFlat, honest sound so you can actually hear what changed between two mixes.
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Audio-Technica ATH-M50x studio headphonesThe go-to pair for spotting small differences between masters.
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beyerdynamic DT 770 Pro headphonesDetailed highs that make a lossy copy easier to catch.
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