What does compression do to an audio signal?

Compression in audio processing is primarily used to reduce the dynamic range of an audio signal. The dynamic range is the difference between the loudest and the softest parts of a recording. By applying compression, the loud sounds are made quieter and the soft sounds are brought closer in volume, resulting in a more uniform sound level. This helps ensure that softer parts can be heard more clearly while preventing the louder parts from overwhelming the mix, ultimately leading to a more polished and balanced audio output.

Other concepts, such as increasing the volume of all sounds, eliminating background noise, or adding reverb effects, do not accurately describe the primary function of compression. Increasing volume would instead involve amplification, while eliminating background noise might require noise gating techniques or filters, and reverb effects are added using different audio processing techniques altogether. Therefore, understanding how compression specifically reduces dynamic range is crucial for audio production and mixing.