Canned laughter, also called a laugh track, is a sound track added to television comedies. It is used during parts of the show when one would expect an audience to laugh, and it may punctuate jokes or moments of slapstick comedy. Not all television comedies where one hears laughter after jokes use canned laughter; some shows record episodes in front of a live audience.
The first use of canned laughter was in the 1950s television series, The Hank McCune Show. The laughter came from a box invented by Charley Douglass. His sound machine was called the Laff Box and delivered a variety of laughs, from giggles, to chuckles to tear producing laughter. Types of laughter could be played separately, much like playing a sample keyboard.
Today’s laugh track is more sophisticated since sound technology has advanced so much. It can be inserted virtually anywhere in an episode, and samples of laughs can range dramatically. Early added laughter often began to sound the same after a while. For example, it’s fairly easy to recognize the same laughs over and again on shows like The Brady Bunch.
Though canned laughter was most often employed on 30-minute sitcoms, sometimes it was used in hour-long shows as well. One unusual use of it was for the series Eight is Enough, which often was not comic. More often, hour-long series like The Love Boat were punctuated with canned laughter that may have helped some laugh along with its comic material.
The idea behind a laugh track is that it provokes the laughter of an at home audience. Laughing can be enjoyably contagious. However, some find the prospect of fake laughter somewhat annoying, as it subliminally attempts to get laughs for comic lines that may be relatively undeserving.
Some recent comic television shows have veered away from canned laughter. Both the British and American versions of The Office, for example, did not employ it. Some claim they enjoy these shows more because they give the viewer an opportunity to laugh freely, without being influenced by an imaginary audience.
Not all shows that are recorded in front of an audience completely use the audience’s laughter. If a joke does not seem to provoke a large enough response, laugh tracks may be added. This is usually referred to as "sweetening" the laugh track.