Speaker driver designed to operate only at the highest frequencies (typically above 10 to 15 kHz), augmenting the output of the tweeter. Super tweeters are sometimes found on the rear side of speakers operating in a semi-bipolar or dipolar configuration to help achieve a smooth frequency response. Super tweeters are fairly rare as traditional tweeters operate all the way up to or beyond 20 kHz in most cases (20 kHz or 20,000 Hz being the upper limit of human hearing). In some cases, fairly large tweeters are used for the upper-midrange and lower-treble (high frequencies) with a super tweeter taking over at higher frequencies. The presence of a super tweeter is of little importance in itself with the determining factor being how a speaker sounds. Most speakers perform fine without the use of a super tweeter, and systems that do use one are designed to take advantage of it.