Processing
Compression ratio defines how much a compressor reduces the level of an audio signal once it exceeds the threshold. It determines the degree of dynamic range reduction and directly affects how noticeable or transparent the compression sounds.
The compression ratio expresses the relationship between input and output levels for signals above the threshold. It is written as a ratio, such as 2:1, 4:1, or 10:1, indicating how much the output increases relative to the input once the threshold has been crossed. For example, with a 4:1 ratio, if the input level rises 4 dB above the threshold, the output will only rise by 1 dB, effectively reducing dynamic range by a factor of four.
Different ratios produce distinct effects. Low ratios (1.5:1 to 3:1) provide gentle, transparent compression suitable for vocals, acoustic instruments, or subtle dynamic control. Medium ratios (4:1 to 6:1) are often used for general mixing tasks, offering stronger level control without sounding unnatural. High ratios (8:1 and above) produce aggressive limiting, while infinite ratio (∞:1) represents hard limiting, where the signal is prevented from exceeding the threshold altogether.
The ratio works in conjunction with other compressor settings — threshold, attack, and release — to determine how dynamically the signal is shaped. A low threshold combined with a moderate ratio can produce smooth, consistent compression, while a high threshold with a high ratio creates more pronounced peak control.
Selecting the right compression ratio depends on the source material and artistic intent. Subtle ratios help retain natural dynamics, while higher ratios are useful for tight, controlled, or creatively exaggerated effects. When used carefully, ratio adjustment allows engineers to balance clarity, punch, and dynamic consistency across a mix.
