The compressor provides level compression. The term compressor is used in audio technology for a component that compresses the level of a signal, i.e. the dynamic range is reduced. Amplitudes with high level values are reduced, those with low level values are increased.
A loud signal thus becomes quieter, while a quiet signal becomes louder. For example, an input signal with a dynamic range of 100 dB can be compressed so that the output signal has only 70 dB.
The purpose of level compression is to increase the volume of soft sounds so that they are still easily audible even in the presence of strong ambient noise, as is the case when driving a car. Other applications of comparators, called limiters in this context, include overload protection, speaker protection, and sound aesthetics.
In terms of technology, a distinction is made between single-band and multi-band compressors in the audio field. While single-band compressors process the entire frequency spectrum as one frequency band, multiband compressors divide a frequency band into several sub-bands that can then be processed separately. A compressor has the opposite function of an expander.