Overdub

Because the process of overdubbing involves working with pre-recorded material, the performers involved do not have to ever have physically met each other, nor even still be alive. In 1991, decades after her father Nat King Cole had died, Natalie Cole released a "virtual duet" recording of "Unforgettable" where she overdubbed her vocals onto her father's original recording from the 1960s. As there is no limit in timespan with overdubbing, there is likewise no limit in distance, nor in the number of overdubbed layers. Perhaps the most wide-reaching collaborative overdub recording was accomplished by Eric Whitacre in 2013, where he edited together a "Virtual Choir" of 8,409 audio tracks from 5,905 people from 101 countries.