01 — The tool
Compress audio dynamics to control louder passages
The free Loudness.ai Audio Compressor reduces level above a chosen threshold. Use it when loud words or musical peaks sit too far above the rest of a recording. Threshold and ratio set how much compression occurs; attack and release control how quickly it responds and lets go.
The compression curve helps explain your settings. With a −24 dB threshold and a 4:1 ratio, a steady level 12 dB above the threshold becomes 3 dB above it, before makeup gain. Knee controls the transition around the threshold. For a fixed peak ceiling, use the Audio Limiter after balancing the recording's dynamics.
02 — How it works
How to compress audio online for free
Find the level differences
Open the recording and listen to the loudest and quietest useful passages. Decide whether the problem is occasional strong words, repeated peaks or a broad difference between sections.
Set threshold, ratio and timing
Lower the threshold until the compressor affects the louder passages. Start with a moderate ratio, then adjust attack and release while listening. Use makeup gain to set the resulting level.
Compare and export
Prepare the preview and compare at similar listening levels. Check transients, breaths and pauses as well as loud sections. Reduce the compression if the result sounds overly flat, then export MP3 or WAV.
03 — Practical uses
Control dynamics in voice, podcasts and music
Spoken-word recordings
Reduce louder phrases that jump out of a narration take. Listen for breaths becoming too prominent after makeup gain. Use the Audio Enhancer first when background noise is the main issue.
Podcast audio
Make strong words less distracting while retaining the speaker's expression. Compression acts on the whole recording; independently recorded speakers may still need separate level adjustments before you combine them.
Music and rehearsal recordings
Tame peaks while retaining the attack and movement of the performance. Compare drum hits, plucked notes and sustained passages. Use Audio Equalizer when the issue is tone rather than changing level.
04 — Frequently asked questions
Audio Compressor questions
Does this audio compressor reduce file size?
It compresses dynamic range, not the file's storage size. To make a smaller audio file, choose MP3 and a suitable bitrate in the Audio Converter. These are different uses of the word compression.
What do threshold and ratio mean?
Threshold is the level where compression starts. Ratio sets how level above that threshold is reduced. At 4:1, four decibels above the threshold become one decibel above it, before makeup gain.
What do attack and release change?
Attack controls how quickly compression responds to a rising level. Release controls how quickly the reduction eases afterwards. Adjust them by listening to the beginnings of sounds and the gaps that follow.
Why should I compare at a similar volume?
A louder preview can seem better simply because it is louder. Use makeup gain carefully and compare the recording's balance and character. Compression should solve the level problem while retaining the expression you need.