Audacity Compressor Settings and Core Parameters

Audacity’s stock Compressor reduces the dynamic range of audio by attenuating loud peaks and evening out the overall volume level. This guide provides a straightforward breakdown of the tool's core parameters—Threshold, Noise Floor, Ratio, Attack Time, and Release Time—along with its key processing options, enabling you to dial in clean, balanced audio for podcasts, music, and voiceovers.

Threshold

The Threshold setting determines the volume level (measured in decibels, or dB) at which compression begins. Any audio that exceeds this level is attenuated, while audio below it remains unaffected. For example, a threshold set to -12 dB means that only audio louder than -12 dB will trigger the compressor.

Noise Floor

The Noise Floor slider sets the lower volume boundary for the effect. Audacity uses this parameter to prevent quiet background hiss, room tone, or low-level bleed from being artificially boosted when dynamic range is reduced. Any signal below this threshold is treated as silence or noise and is not amplified.

Ratio

The Ratio dictates the amount of gain reduction applied to audio exceeding the Threshold. Expressed as a ratio (such as 2:1, 4:1, or 10:1), it indicates how much input level is needed to produce a 1 dB increase in output level. A 2:1 ratio represents gentle, transparent compression, while higher ratios like 6:1 or above provide aggressive limiting.

Attack Time

Attack Time controls how quickly the compressor responds once the audio signal crosses the Threshold. A fast attack time (e.g., 0.1 seconds) clamps down immediately on sudden transients like drum hits or loud plosives, while a slower attack allows the initial punch of the sound to pass through before gain reduction engages.

Release Time

Release Time determines how long it takes for the compressor to stop attenuating the signal once the audio drops back below the Threshold. A short release time quickly restores the volume, which can create a pumping effect if set too fast, whereas a longer release creates a smooth, natural transition back to unity gain.

Additional Compression Options

• Make-up gain for 0 dB after compressing: Automatically amplifies the processed signal so that the highest peak reaches 0 dB, restoring perceived loudness lost during gain reduction.
• Compress based on Peaks: When unchecked, Audacity applies RMS (Root Mean Square) compression, which responds to perceived average volume. When checked, the compressor reacts directly to the absolute peak volume levels.