An audio compressor is a device used in audio production to smooth out differences in sound level between different parts of the audio signal. This is done to achieve a more balanced and controlled sound. Let me explain how an audio compressor works:
- Input signal (Input): The sound compressor receives an input signal, which can vary in strength.
- Threshold: The sound compressor is set with a threshold value. The sound must exceed this threshold value for the compressor to start working. If the sound is below the threshold, it remains unchanged.
- Ratio: When the sound level exceeds the threshold, the ratio affects how the compressor reduces the volume. The ratio indicates how much compression should be applied for each decibel (dB) of sound above the threshold. For example, if the ratio is set to 4:1, every 4 dB above the threshold will be reduced to 1 dB.
- Attack and Release: These parameters control how the compressor reacts to sound that exceeds the threshold. "Attack" refers to how quickly the compressor reacts, while "Release" indicates how quickly the compressor stops working after the sound has fallen below the threshold.
- Output: After the compressor has adjusted the sound level according to the settings, it emits an output signal with smoother dynamics.
For example, if you have a vocal recording where some parts are very loud and others very quiet, an audio compressor can reduce the differences so that the vocals remain audible and balanced throughout the recording. Sound engineers use compressors to improve sound quality, control dynamics and provide a more professional soundstage.