A very brief excerpt of speech or film used esp in political campaigns to make a quick impression: They present him chiefly in a staccato series of sound bites(late 1980s+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with sound bite
A short, striking, quotable statement well suited to a television news program. For example, He's extremely good at sound bites, but a really substantive speech is beyond him. This slangy expression, first recorded in 1980, originated in political campaigns in which candidates tried to get across a particular message or get publicity by having it picked up in newscasts.