Sibilance occurs when we say ‘ess’ sounds like the letters ‘s’, ‘t’ and ‘z’. It’s that loud harshness that makes those particular syllables jump out of a recording. These syllables are concentrated in the upper mid range frequency (between 5kHz and 8kHz) and are caused by disproportionate audio dynamics. 

Speaking into a microphone is like whispering in someone’s ear. Usually we don’t do this and so the higher frequency sounds lose energy as they travel from the speaker’s mouth to the listener’s ear. However, this doesn’t happen when you are close to your mic, and so those sounds are more pronounced.

It’s also worth noting that people with gaps between their front teeth are more susceptible to sibilance, so if that’s you pay particular attention to this section! 

Sibilance can be dealt with effectively in post production using the ERA 4 De-Esser, we’ve got a whole article on that, but it can be reduced in the recording stage too.

Distancing yourself from the mic about 25 to 35cm can help, as can angling the mic downwards by about 10 degrees. Additionally, if you have a very bright voice it may be worth investing in a darker microphone, ie one with less pronounced upper mid range frequencies.