There are four different types of lisps, each with distinct characteristics lisp sounds related to the tongue placement.
Interdental Lisp or Frontal Lisp - occurs when the tongue protrudes or sticks out between the teeth when making "s" or "z" sounds, resulting in a "th" sound.
Dentalised Lisp or Dental lisp - occurs when the tongue rests or pushes up against the front teeth, resulting in a muffled sound.
Lateral Lisp - occurs when extra air flows over the sides of the tongue instead of down the middle, resulting in a slushy lisp sound.
Palatal Lisp - occurs when the tongue tip touches the roof of the mouth (also called the soft palate) when making "s" or "z" sounds rather than behind the teeth.
Lisps can impact clear communication and self confidence. Untreated children's lisps can impact typical speech development, self esteem and lead to speech delay and cause other long-term speech errors.