Sibilance

A sibilant is a type of fricative or affricate consonant, made by directing a jet of air through a narrow channel in the vocal tract towards the sharp edge of the teeth.In audio recording sibilance at times can be considered undesirable and a process known as de-essing is used to filter or attenuate the undesired frequencies.

Sibilants are louder than their non-sibilant counterparts, and most of their acoustic energy occurs at higher frequencies than non-sibilant fricatives. [s] has the most acoustic strength at around 8,000 Hz, but can reach as high as 10,000 Hz. [ʃ] has the bulk of its acoustic energy at around 4,000 Hz, but can extend up to around 8,000 Hz.