A signal processing technique that reduces the volume difference between the loudest and quietest parts of an audio signal.

Dynamic Range Compression

Dynamic range compression (often simply called compression) is a fundamental audio processing technique that automatically controls the amplitude of audio signals by reducing the dynamic range - the span between the loudest and quietest parts of the sound.

Core Principles

The compression process involves:

Monitoring input signal level
Comparing it to a user-defined threshold
Reducing signals that exceed the threshold according to a ratio
Applying timing controls through attack time and release time

Key Parameters

Threshold

The decibel level above which compression begins to take effect. Signals below the threshold pass through unchanged, while those above get reduced.

Ratio

Determines how much compression is applied, expressed as X:1, where:

2:1 is gentle compression
4:1 is moderate compression
10:1 or higher approaches limiting

Attack and Release

Attack time: How quickly compression engages
Release time: How quickly compression disengages These settings are crucial for maintaining natural dynamics

Applications

Music Production

Evening out vocal performances
Controlling bass dynamics
Creating punch in drums
Achieving mix cohesion

Broadcasting

Ensuring consistent loudness levels
Meeting broadcast standards
Improving speech intelligibility

Live Sound

Protecting equipment from peaks
Managing stage volume
Enhancing overall clarity

Types of Compression

Side Effects

While compression is essential in modern audio, improper use can lead to:

Historical Context

Compression evolved from early broadcast limiters in the 1950s to become an indispensable tool in modern audio production. The technology has shaped the sound of modern music, leading to ongoing debates about the loudness war in commercial music.

Best Practices

Set appropriate attack times to preserve transients
Use gentle ratios for natural-sounding results
Monitor both compressed and uncompressed signals
Consider parallel compression for complex material
Match compression style to genre expectations

Dynamic range compression remains one of the most important and frequently used tools in professional audio, balancing technical necessity with creative application.