Mid/Side processing is a technique that processes stereo signals. Within this process, the signal has two mono signals. One of them is specifically for the left channel, while the other one is for the right. Although some signals might emerge from the center when creating a stereo signal, most of the sounds take place either on the left or on the right sides.
Mid/Side processing does not change the stereo signal. For this reason, engineers commonly use it in conjunction with equalization or compression tools. During the mid/side processing, the left and right stereo signals separate into a mid and a side-channel. Achieving this makes it possible to compress or equalize the sounds found in the center of a mix on one side and the side sounds on the other.
Mid/Side Processing: Deselection Tools
Deselection tools are essential. The most frequently used ones are mid/side processing and multi-band processing. Firstly, mid/side processing involves the left and right channels of a typical audio signal. Secondly, multi-band processing is also widely popular. It involves a two-track stereo mix divided into up to four frequency bands. With this tool, the user can decide the amount of compression needed for a frequency band. This multi-band selection allows the engineer to shape both the dynamics and the timbre of the final project.
The Processing Itself
In simple terms, mid/side processing happens when a signal is fed at an equal amplitude to both the left and the right speaker. This, in turn, creates a phantom center image. In brief, it gives the impression that there is a third speaker positioned equidistant between both speakers.
As we have mentioned before, the mid signal is the sum of the left and the right channel. In the stereo image, the difference between the two channels has control over the mid and the side of the master. By managing the master with mid and side controls, rather than with left and right controls, the user gets a different perspective. Also, s/he can distinguish between equalization and compression applied to the instruments in the center of the mix and the signals that exist on the sides.
