A special limiter, or limiter circuit, that is used to cut high-end frequencies. It is called a "de-esser" because it is often used to eliminate the vocal distortion created when pronouncing words that include the letter "s". Device for reducing the effect of sibilance in vocal signals. Basically, a de-esser is a frequency dependent compressor, although these days such devices are very sophisticated and optimized in the way they tackle the problem of sibilance. This article is a stub awaiting insertion of the theory behind de-essers and sidechains.