How Sibilance Affects Sound

Music equalizer background
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If you listen to enough music, you'll eventually come across situations where the vocals you hear can sound a little off. A little raw, biting, or harsh. Maybe a little like someone threw an agitated, serpent into the track recordings. It doesn't take long for the music to feel a little draining, causing general fatigue from extended listening sessions. If any of this sounds familiar, then you've experienced the undesirable and often unpleasant effects of sibilance.

Sibilance is a sound characterized by pronouncing consonants, syllables, or words with the letter 's' (and sometimes a 't' or 'z'). It frequently refers to vocals versus other aspects of music (e.g. instruments, distortion, etc.). 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. But, such 's' sounds can seem particularly sharp, bright, or even piercing when reproduced by audio systems. It can happen infrequently or by the mouthful, 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

There are a number of factors that can contribute to experiencing 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 sounds together. While this 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 the top audio equipment can't 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 and/or re-digitizing at a higher quality. But, sometimes the source of sibilance comes about from 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.