Vocal sibilance is an unpleasant tonal harshness that can happen during consonant syllables (like S, T, and Z), caused by disproportionate audio dynamics in upper midrange frequencies. Sibilance is often centered between 5 kHz to 8 kHz, but can occur well above that frequency range.
This problem is usually caused by the actual vocal formant, but can also be exaggerated by microphone placement and technique. This article will discuss some ways to control vocal sibilance, and keep the problem from becoming a musical distraction.
Sibilance at the Source
(best read with sibilant whistle)
In phonetic terms, sibilance comes from a type of vocal formant called a fricative consonant. During these sorts of utterances, the airway (usually the mouth) is drastically constricted by two anatomical features, like the teeth, tongue, or palette.
This pressurization causes some amount of noise that forms the consonant sounds we would recognize from a phase like, “Sally sits sideways on the tennis trolley.” Sibilance is a very necessary feature of human speech, but when there’s (subjectively) too much noise created during these consonants, we get a very distracting harshness.
It isn’t really practical or productive to address micro-muscular vocal technique during a session, so your best bet to mitigate sibilance at the source is microphone selection and placement. Here are a few suggestions:
—Every vocalist is remarkably different, so don’t pre-suppose that anything you’ve tried before will or will not work again.
—Be sure to leave some space between your vocalist and the microphone. Twelve to eighteen inches would be a nice starting point.
—A pop filter won’t do anything to help with sibilance.
—Once you find a microphone and distance combination that helps, try angling the microphone downward 10 to 15 degrees to place the 0-degree axis toward the throat instead of the sibilant source.
Audio Dynamics Processing
Vocal sibilance is a phenomenon of disproportionate dynamics within an isolated frequency range. In other words, it is a problem of too much loudness contrast within a small frequency range of a waveform that has a dynamic profile of its own.
‘De-essing’ is the classic compressor technique used to address vocal sibilance through processing. In fact, de-essing is just one example of many uses for compression that is conditioned on a limited frequency band, or a modified harmonic profile.
