Normalize audio online

How to normalize an audio file

The Normalize window opens as soon as your file has loaded.

1. Click Open a file to normalize, or use File ▸ Open… (Ctrl+O), and choose your audio file.
2. Leave the selection empty to normalize the whole file, or select one part to normalize only that part.
3. Open Effects ▸ Amplitude ▸ Normalize… if it is not already open.
4. Set Normalize to. It goes from -30 to 0 dB and starts at -0.1 dB; -1 dB leaves a little headroom, which helps if you will export MP3.
5. Keep DC Bias Adjust ticked, and leave Normalize channels independently unticked unless you need it.
6. Press Preview to listen, then click OK.
7. Save the result with File ▸ Save As… in the format you need.

What Normalize does, and what it does not

Normalize in Auditius is peak normalization. It measures the single highest sample and applies one fixed gain to the whole selection, up or down. Because the target is never above 0 dB, it does not clip.

It does not measure loudness the way your ears do. Two files normalized to the same peak can still sound different: a song with a few sharp drum hits sounds quieter than a heavily compressed one. Auditius has no loudness (LUFS) normalization.

• The distance between quiet and loud parts stays the same. Normalize does not compress or change the dynamics.
• One stray click can hold the whole file down. Remove it with Effects ▸ Noise Reduction ▸ Click / Pop Eliminator… or lower it by hand, then normalize again.
• A target below the current peak makes the file quieter. Normalize always moves the peak to the target, in either direction.

The two options in the Normalize window

Both options are about how the peak is measured.

• DC Bias Adjust, on by default, removes any DC offset before measuring: a constant shift of the wave away from the center line. An offset wastes headroom and can cause clicks at edits.
• Normalize channels independently brings each channel of a stereo file to the target on its own. Use it when one side was recorded quieter by mistake; avoid it on music, because it changes the stereo balance.
• Check the result in Analyze ▸ Statistics…: Peak Amplitude should show the value you chose, and DC Offset should be close to zero.

Normalizing many files at once

To bring a set of songs or episodes to the same peak, record the step once and run it as a batch. Start a script with Edit ▸ Scripts ▸ Record Script, normalize an open file with nothing selected, and end it with Edit ▸ Scripts ▸ Stop Recording.

Then open File ▸ Batch Process…, choose the open files or files from disk, pick your script and decide whether to export the results or open them as new files. Each file is measured on its own, so every result peaks at the same level.