Fold-Down

The process of taking a certain number of audio channels and restructuring them in fewer channels. The fold-down process is most commonly used to reproduce surround sound mixes in a stereo format. When starting with a 5.1 mix the process involves integrating signals that were originally sent to the subwoofer and taking the center channel signal and creating a “phantom center.” In addition, any audio sent to rear channels must be integrated into the stereo mix. This is often the tricky part, as signals that have been decorrelated to produce a front-to-rear sense of space must be carefully handled to avoid phase cancellation in the stereo mix. This process is also sometimes referred to as downmixing.