A tweeter is a loudspeaker that produces high frequencies. The range of frequencies is typically from around 2000 Hertz to 20,000 Hertz (generally considered to be the upper limit of human hearing) but some tweeters reach up to frequencies of 30,000 Hertz and one exotic example is claimed to reach up to 100,000 Hertz.
In home stereo systems most tweeters are dynamic small dome diaphragms of 1 inch in diameter or less.
Tweeters for sound reinforcement and public address applications are often horn loaded piezoelectric speakers. The horn increases the efficiency and directivity of the speaker.
See also