Overview
Compression is the most misunderstood tool in audio production. It doesn't make audio louder — it reduces the dynamic range (the gap between quiet and loud) so the whole performance can sit at a more consistent level. Once you understand the four main controls, you can use compression purposefully rather than by guessing.
What You Need
- Any compressor plugin (your DAW's built-in works fine for learning)
- A vocal or podcast recording with dynamic variation
- Headphones or monitors
Steps
What compression actually does
A compressor is an automatic volume control. When the signal exceeds a set threshold, the compressor turns it down by a set ratio. That's the entire concept. The artistic magic comes from choosing when (threshold), how much (ratio), how fast (attack), and how long (release) to apply that volume reduction. Use our Dynamic Range Compressor tool to see the transfer curve visually.
Set the threshold
The threshold is the level above which compression begins. Lower the threshold until the gain reduction meter is moving on the loudest phrases. For voice: start around −18dB and adjust until you see 4–8dB of gain reduction on peaks. If nothing is being compressed, lower the threshold. If it's always compressed, raise it.
Choose your ratio
The ratio determines how aggressively levels above the threshold are reduced. 2:1 is gentle — 2dB above threshold becomes 1dB above. 4:1 is medium — used for most podcast vocals. 8:1+ is heavy limiting. For podcast and VO: 3:1 to 4:1 is the target range. Above 8:1 starts to sound squashed unless that's intentional.
Set attack and release
Attack is how quickly compression kicks in after the signal exceeds the threshold. Slow attack (20–50ms) lets the initial transient through before clamping down — preserving the "crack" of consonants. Fast attack (1–5ms) catches everything, sounding more controlled but less natural. Release is how quickly the compressor lets go. For voice: attack 10–30ms, release 60–200ms. A release that's too short causes pumping; too long causes the compressor to never fully open between words.
Apply make-up gain
Compression turns loud things down, which makes the overall level lower. Make-up gain brings it back up — so the compressed signal matches (or slightly exceeds) the uncompressed level. Without make-up gain, the compressed version sounds quieter and you incorrectly judge it as "worse." Many compressors have an auto make-up gain option; it's fine for learning but manual control is more precise.
Check the gain reduction meter
Watch the gain reduction meter while the audio plays. You want it moving actively on the loudest moments — if it's pinned continuously, your threshold is too low or ratio too high. Aim for the needle swinging between 0 and −8dB on peaks, with quieter sections showing near zero. That's the sign of transparent, working compression.
Pro Tips
- The bypass test: toggle the compressor on and off while matching perceived volume with make-up gain. If you can't tell the difference, you've set it well.
- Two light compressions in series (4:1 + 2:1) often sounds more natural than one heavy compression (8:1).
- Audacity's built-in compressor is fine for podcasts. For more control, try the free Airwindows plugins or TDR Kotelnikov.