Compression is the process carried out by sound engineers across the Film, Radio, and TV industry to control the extreme variations in sound levels and makes a piece of music more pleasing to hear. The specialized device used to execute this task is called a Compressor. Without the compressor, you would have to keep increase and decreasing the volume of the audio, as suddenly some levels would go up and then down.(If you have to do it while watching a movie or a tv series, the compression has not been applied properly!)
An ideal compressor consists of a sound detector circuit which automatically responds to average loudness of the received audio signal. If the signal goes above a particular level, the compressor reduces the level and maintains a uniform volume.
In the example picture below, the audio signal on the right is uncompressed and so has lots of peaks. the signal on the left is compressed and so has a uniform signal level.
It manages signal levels
A sound engineer maintains consistent volume of the sound recorded. For instance, a musical instrument such as the piano has an extremely wide dynamic range, which an audio engineer balances effectively by boosting the levels when the piano plays the softest and reducing it when the instrument is playing the loudest. However, it is physically almost impossible to keep track of each of such irregularity in volume peaks, and manually adjust the levels. An audio compressor works automatically, reducing sound levels during durations of loud volume instantly and precisely and makes life easy for a sound engineer. Using compressor is the best way to limit the dynamic range while keeping the sound quality intact.
Adding punch and character to the audio
Compressors can add, more punch and presence to the audio tracks, especially on Voice, drums and bass tracks. It adds vigor and gives an individuality to the recordings. Let’s understand how a compressor is used for generating the above. If the compression applied is heavy, it ends up subjecting the same level of input audio through a narrower aperture. This results in the following:
a) Higher signal level at lower volumes
b) Maintenance of lower frequencies of certain musical instruments like guitar, piano, and bass.
c) Strong, even and dynamically constant quality of sound that brings about a certain depth making it sonorous.
d) If the compressor settings are programmed to be more reactive, an audio engineer can achieve optimum level of punch on drums and guitar
It enhances sound effects
The compressor settings can be altered to use compression as a variety of stunning sound effects. A good compressoracts as a bridge between your audio source and sound recording equipment chain, setting limits for received audio signals. The sound effects can be made more bizarre, punchy or cutting through proper compression
The audio compressor audio effects impart a unique flavor and a wonderful effects to the sounds we hear almost daily in the broadcast industry. The richness and density in the voice quality of announcers has much more to it than seems to our ears. It owes a lot to perfect equalization and intense dosage of compression. The effects of strong compression are often felt prominently while watching a program on the TV, when the loud volume of advertisements acts as a bolt from the blue. The whole idea is to cram the maximum level of signal into a narrower range, to vie against competing stations in terms of a higher levels of volumes..
By Rajiv Agarwal