Dynamic range compression (DRC) or simply compression is an electronic effect unit that reduces the volume of loud sounds or amplifies quiet sounds by narrowing or "compressing" an audio signal's dynamic range. A dedicated electronic hardware unit or audio software that applies compression is called a compressor. Please refer to our OpenDRC Series, the nanoAVR HD/HDA/DL products, the 2x4, the 2x4 HD, the 10x10 HD.

(Source: wikipedia.org)