In sound design sweetening ("to sweeten") refers to "juicing up" the video portion of a film, play, computer game software or any other multimedia project. Its origin may have been old-time radio, which produced visual detail with sound effects such as people walking, horses galloping, doors opening and closing, gun shots, "body slams," etc.
In the case of a music performance or recording, sweetening may refer to the addition of additional instruments such as that found on The Sounds of Silence by folk troubadours Simon and Garfunkel. The original acoustic version of the song features just the two of them and one guitar. Producers at Columbia Records, however, felt that it needed a little spicing up to be a commercial hit, and so without the consent of the artists, they added drums, electric bass and electric guitar.
In television sweetening refers to the use of a laugh track in addition to a live studio audience. The laugh track is used to "enhance" the laughter for television audiences, sometimes in cases where a joke or scene intended to be funny does not draw the expected response, and sometimes to avoid awkward sound edits when a scene is shortened or more than one take is used in editing.[1] Sweetening has been used in a number of television series, even ones that have been successful popularly or with critics: Happy Days, Taxi, The Mary Tyler Moore Show, etc.[2] The act of sweetening is demonstrated in the Woody Allen film Annie Hall when Alvy Singer visits his friend Rob, played by Tony Roberts, in Los Angeles. At one point, Rob has the engineer add laughter to cover voiced disapproval from the audience. Some shows used the canned laughter technique very obviously rather than the "in-between" technique (a recording from an external audience, but genuine laughter) described as a laugh track. An obvious sign of this is that the laughter is more or less identical in volume or magnitude, regardless of how extreme the joke is.