Recording studio technique
Ping ponging, also known as bouncing , is the process of recording a mix of several tracks on a multitrack recorder onto one or two tracks of the same recorder. The original tracks are then free for recording new instruments.
A drum kit for example can take up as many as eight to ten tracks on a 24 track system. If, for any reason, the remaining 14 tracks are not enough, one can free up some of the drum tracks by making a stereo mix to two internal channels, called group buses, on the mixing console, where one bus serves as a left stereo channel and one as right. The bus outputs can then be fed back into the multitrack recorder to be recorded on two free tracks. The original loose drumtracks are then free to be reused.
This is a tradeoff between flexibility and space. Drum sounds can no longer be processed individually during mixdown but the drums will now only occupy two tracks, leaving the remaining 22 tracks free. Like all signal manipulations it tends to degrade the sound quality and affect the signal to noise ratio negatively.
A word of caution: when ping ponging on an analogue multitrack system, make sure your destination tracks are not physically adjacent to any of the source tracks on the tape. Analogue systems always have a degree of cross-talk between channels, no matter how expensive the equipment is. This might cause feedback during the procedure.