What Is Sibilance and How Does It Affect Sound?

A snake-like hiss from exaggerated 'S' sounds? That's sibilance

Music equalizer background
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If you listen to enough music, you'll eventually come across situations where the vocals sound a little off—a little raw, biting, or harsh. Maybe a little like someone threw an agitated serpent into the track recordings. You've experienced the undesirable and often unpleasant effects of sibilance.

What Is Sibilance?

Sibilance is a sound characterized by pronouncing consonants, syllables, or words with the letter S (and sometimes a T or Z). It often refers to vocals rather than other aspects of music, but it may also stem from pitchy instruments like high-hat cymbals. In audio reproduction, the letter S should sound clear and distinct, not smeared, exaggerated, or distorted as in sh or ch. If the letter S sounds like it's being hissed instead of sung, then sibilance is most likely the culprit. 

How Sibilance Occurs

Sibilance is a natural part of human speech and integral to the way words are formed across many different languages. Repeat, "Sally sells seashells by the seashore," a few times quickly, and you'll have a good idea of the kind of noise that sibilance creates. These sounds can seem particularly sharp, bright, or even piercing when reproduced by audio systems. It can happen frequently or infrequently, whether music is being listened to by headphones or speakers. Sibilance often occurs when being sung in the upper mid-range and above.

How to Reduce Sibilance

Several factors contribute to undesired sibilance. One easy fix is to turn the music down. Excess volume tends to exacerbate the effect of sibilance through distortion when the audio signal becomes too high for drivers or components. Another alternative is to adjust the frequencies using an equalizer, correcting only the affected ranges instead of all the sounds together. While this step can help, it will also change the music's overall presentation.

With sound, equipment matters. Lower-end speakers, headphones, and components (e.g. amplifiers, receivers, cables, etc.) won't be as capable or accurate as better gear from respected manufacturers. The source matters, too. Even top audio equipment cannot compensate for low-quality digital audio files. So if you're still stuck listening to 128 kbps MP3s, it might be a good time to consider other formats or re-digitizing at a higher quality.

Sometimes the source of sibilance comes about during the recording process itself. Microphone quality and placement, vocalist enunciation, and recording tools are just some of the things that can all play a part in how much sibilance exists in the final result.

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