Wild track, also known as wild sound and wild lines, is an audio recording intended to be synchronized with film or video but recorded separately. Generally, the term "wild track" refers to sound recorded on location, such as sound effects gathered when the cameras were not rolling or extra takes of lines performed for audio only.

Reasons to record wild track

• When only the sound is needed, not the image; for example, recording a scream that will be heard off-camera.
• When it is impossible to get good sound and video in the same take; for example, when actors are in a situation (such as the middle of a field in wide shot) that makes boom
  Boom operator (media)
  A Boom operator is an assistant of the production sound mixer. The principal responsibility of the boom operator is microphone placement, sometimes using a "fishpole" with a microphone attached to the end and sometimes, when the situation permits, using a "boom" which is a more intricate and...
  
   recording impractical and no wireless mics are available.
• When a take was good visually but there was a sound disturbance, and repeating the entire take is impractical.
• To obtain room tone (the background noise of a location) which is necessary for post-production sound editing.
• To create a censored version of a vulgar or suggestive piece of dialogue for television
  Television
  Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
  
   or radio
  Radio
  Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
  
   viewing in post-production. Specifically, a less vulgar version of the same line may be transposed seamlessly over the original. A notorious example is the famous line from Snakes on a Plane
  Snakes on a Plane
  Snakes on a Plane is a 2006 American horror-action-thriller film directed by David R. Ellis and starring Samuel L. Jackson. It was released by New Line Cinema on August 18, 2006 in North America...
  
  : the televised version has Samuel L. Jackson
  Samuel L. Jackson
  Samuel Leroy Jackson is an American film and television actor and film producer. After becoming involved with the Civil Rights Movement, he moved on to acting in theater at Morehouse College, and then films. He had several small roles such as in the film Goodfellas before meeting his mentor,...
  
  's character utter, "I have had it with these monkey-fighting snakes on this Monday-to-Friday plane!"

Note that wild track is considered something of a "cheapie" solution to these problems, and a big-budget production is more likely to use studio-recorded sound in these situations, as its quality is more controllable and predictable than wild track.

Procedures related to wild track

• Dubbing
  Dubbing (filmmaking)
  Dubbing is the post-production process of recording and replacing voices on a motion picture or television soundtrack subsequent to the original shooting. The term most commonly refers to the substitution of the voices of the actors shown on the screen by those of different performers, who may be...
  
  , Automated Dialogue Replacement, in which actors read their lines in a studio setting to match lip movements already filmed.
• Voiceover
  VoiceOver
  VoiceOver is a screen reader built into Apple Inc.'s Mac OS X, iOS and iPod operating systems. By using VoiceOver, the user can access their Macintosh or iOS device based on spoken descriptions and, in the case of the Mac, the keyboard. The feature is designed to increase accessibility for blind...
  
  , in which a voice track is used but not synchronized with onscreen action.
• Foley
  Foley artist
  Foley is the reproduction of everyday sounds for use in filmmaking. These reproduced sounds can be anything from the swishing of clothing and footsteps to squeaky doors and breaking glass. The best foley art is so well integrated into a film that it goes unnoticed by the audience. It helps to...
  
  , in which sound effects are created in a studio.
• Scratch track
  Scratch track
  Scratch track may refer to* scratch race, also called scratch track race* scratch track, a sound recording used as a temporary placeholder during the recording and editing process* Scratch Track, an American band...
  
  , a temporary sound recording intended to be replaced later.