raditional de-essers use compression techniques. In addition to the threshold parameter used to set the processing level, there is a frequency controller for setting the center frequency of the process (with bandwidths generally up to 4 kHz). Processing therefore compresses the entire selected range, notjust the sibilant or S sounds. This results in the familiar and undesired side-effects such as lisping and a nasal-sounding vocal.

The SPL De-Esser is a highly specialised audio tool for removing undesired sibilant frequencies in a very simple and musical way without compromising the timbre and natural character of a voice.

To solve this difficult problem, SPL has developed a new circuit design that combines ease of use with natural sound characteristics and the highest level of technical performance. The SPL De-Esser monitors the S-frequency spectrum and automatically detects the sibilant frequencies. The de-ess bandwidth is set so narrowly around the range of the sibilance that neighbouring frequencies remain unaffected. Input processed via this frequency band is mixed back into the main signal phase-inverted so that only the S-sounds are cancelled where the S-reduction controller determines the intensity of the phase-cancelled mix. The result is a neutral, unobtrusive and extremely effective de-essing process. Even at high S-reduction values the de-essing has a negligible effect on the character and timbre of the voice.

Rounding out the amazingly simple control system is an automatic threshold-adjusting function. Differences in the input level caused by the varying distance to the mic, are compensated for automatically. This ensures even de-essing independent of signal level so any necessary compression may be applied post the de-esser.