Deesser

Deesser is an audio processing tool designed to reduce sibilance in audio recordings, most commonly on vocal tracks. Sibilance refers to the harsh hissing sounds produced by consonants such as s, z, sh, and ch, which can become prominent after recording or during loud passages. A deesser attenuates energy in a narrow high-frequency range where sibilants reside, typically around 5 kHz to 8 kHz, though exact frequencies vary by voice and style.

How it works: A deesser monitors a target frequency band or uses a sidechain fed from the main signal. When the energy in the band exceeds a threshold, the processor reduces gain in that band, usually via a compressor or dynamic EQ. Lookahead and fast attack times help catch transient sibilants, while release times control how quickly the effect subsides.

Types: De-essers can be standalone hardware units, software plugins, or features of dynamic EQs and multiband compressors. Some use fixed center frequencies, others offer adjustable frequency and bandwidth to tailor control to a voice. More advanced tools may use spectral detection for precise targeting.

Applications and considerations: Common in mixing and mastering vocal tracks to improve intelligibility and reduce listener fatigue. Settings should balance attenuation with natural brightness; typical controls include threshold, ratio, frequency, bandwidth, attack, and release. Overuse can yield a dull or unnatural sound.