Overdub

Overdub is a recording technique in which new audio is recorded on top of an existing recording, creating layered tracks. It is a staple of multitrack recording used to add vocals, instruments, or effects after an initial performance has been captured. The practice emerged from analog tape studios in the 1950s and 60s, when engineers discovered they could play back a performance on one track while recording new material on another.

In a typical workflow, a guide or reference track is established. The performer records the overdub on a separate track while listening to the existing material and a metronome or click track. In analog setups, latency is not an issue with direct monitoring; in digital setups, latency compensation ensures samples align.

Overdubbing enables comping: multiple takes are recorded and then the best sections are assembled into a final performance. It is widely used for vocal harmonies, guitar and keyboard layers, percussion, and sound design. It can also be used to replace parts without re-recording entire sections.

In modern software, overdub functionality is integrated into digital audio workstations and can include punch-in overdubbing, where only selected regions are recorded while playback continues. The concept is distinct from overdub-like features such as synthetic voice generation, which is sometimes marketed under "Overdub" in speech tools, though unrelated to musical overdubbing.