In multi-channel recording, the pan pot or pan setting allows one to place a sound track so that it will primarily come from the left speaker, middle (both), or right speaker. Each track has its own 180-degree pan setting adjustment. By placing certain sound effects, instruments, and voices, in different spatial locations ranging from far left to far right, playback of the combined tracks creates a spectral feeling, putting the listener inside the acoustic envelope.
In standard musical recordings, drums and lead vocal are typically centered, coming equally from the left and right channels or speakers. Piano or organ might be placed slightly to the left, while bass might lay just to the right of center. Lead guitar and rhythm might take up opposite extremes. Using the pan setting of each track, the band is essentially spread out in a semi-circle around the listener.
Aside from initial placement, the pan setting is also used for special effects. In an instrumental break for example, a hard guitar riff might rip from the left channel, while an answering riff duels from the right. The listener not only hears the music, but thanks to the pan settings, feels the spatial extremes of the acoustic environment.
Another effect created with the pan setting, is movement. A drum roll might go from far left to far right, creating the effect of rolling past or through the listener. This effect is also used with organ riffs and other instruments. If overused or misused, it can be distracting.
Pan setting is perhaps most obvious in surround sound theaters where placement of sound effects is crucial in building a convincing sound track. In this case acoustic movement from side to side or from front to back is a common occurrence, used for people walking through a shot, for passing traffic, airplanes flying overhead, and so on.
Sound tracks encoded for surround sound automatically channel appropriate sound effects to rear speakers to complete the 360-degree audio environment. If rear speakers are not available, these tracks are mixed into the available speakers in the next best configuration. Where stereo speakers are the only option, all tracks are sent to the two speakers. The quality of sound might be very good (providing the speakers are excellent) but the acoustic envelope is less convincing with fewer speakers.
The pan pot is just one setting of many that can be used to manipulate or contour sound in multi-channel recordings. It is available on nearly all devices of this type. Without it, reproducing acoustic “space” would be very difficult.