Do you know someone who put their tongue between their upper and lower teeth when pronouncing 's' or 'z' and pronounce them as the 'th' in think? That’s a lisp.

A lisp (also called sigmatism) is a common and treatable speech impediment involving mispronunciation of sibilant sounds. Sibilants are speech sound produced with a hissing effect, e.g. s, z, sh.

It is common among children but usually disappear before the age of six. However, some have it till adulthood. The main known cause of a lisp is wrong tongue placement.

The three types are frontal lisp, dental lisp and palatal lisp.

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