Sibilance
Harsh, piercing “s” and “sh” sounds in recorded speech caused by high-frequency energy concentration, often managed through microphone technique and de-essing.
Sibilance refers to the exaggerated harshness of fricative consonants, particularly “s,” “sh,” “z,” and “zh” sounds. These consonants naturally concentrate acoustic energy in the 4 kHz to 10 kHz frequency range, and when recorded with a sensitive condenser microphone at close range, they can produce piercing, almost whistling sounds that are fatiguing to listeners. Sibilance is especially problematic in audiobook production because listeners wearing headphones for extended periods are particularly sensitive to it.
Microphone technique is the first line of defense. Recording slightly off-axis (angling the microphone 10 to 20 degrees rather than speaking directly into the center of the capsule) reduces the high-frequency energy hitting the diaphragm. Increasing your distance from the microphone by an inch or two also helps, though this affects proximity effect and may require gain adjustment. Some narrators place a pencil vertically in front of the microphone capsule to physically split the airstream of sibilant sounds, which is surprisingly effective.
When prevention is not enough, de-essing is the standard post-production solution. A de-esser is a frequency-specific compressor that detects sibilant energy and temporarily reduces gain in the problematic frequency range. Most DAWs include a de-esser plugin, and dedicated tools like FabFilter Pro-DS offer more precise control. The goal is to tame the harshest sibilant peaks without making the narrator sound like they have a lisp, which is the telltale sign of over-processing.