Compression

• Compression affects changes in volume of a signal in real-time. When the volume exceeds the threshold, compression begins.
• Ratio determines the amount of compression after the threshold is exceeded. Example: If the threshold is 0dB, the ratio is 2:1 and the incoming signal is 10dB then the resulting signal will be 5dB. At a 4:1 ratio the result would be 2.5db.
• Some compressors feature attack and release controls. The attack time determines how long it takes to reach the full ratio of compression after the threshold is exceeded. Release time affects how long the effect will last once the signal has dropped below the threshold.
• Limiting, or peak-limiting, contrasts to compression in that the signal is never allowed to exceed the threshold. It just stops at that volume, like a brick wall. Limiting is useful for protecting sound systems from transient peaks or for preventing "overs" in digital recording but generally I avoid limiting unless I'm using it as an effect similar to distortion.