You are likely familiar with this frustrated statement:
Whose idea was it to put an /s/ in the word lisp?
For lisp-ers of all types, /s/ is the quintessential challenging sound. However, /s/ is not the only sound impacted by lisps. Lisps can impact a variety of sounds depending on the cause and the type of lisp. Some lisps are developmental until a certain age, while others should be addressed by a speech-language pathologist.
Before diving into atypical productions of /s/, let’s learn how /s/ is typically created by the speech structures.
The /s/ phoneme is a fricative (i.e., sound requiring forward airflow) produced by the tip of the tongue making contact with the alveolar ridge (i.e., the bumpy part on the roof of your mouth right behind your top two front teeth). The back sides of the tongue simultaneously seal with the top back molars (to prevent air escape!) while air moves over the tip of the tongue and through the teeth; that is how we get the hissing-like /s/ sound!
So what happens with all those moving parts for /s/ don’t happen? You get a variant production of /s/! Maybe a ‘th’ or more distorted sounding /s/. These variant productions are commonly known as “lisps.” There are four primary types of lisps:
Frontal or Interdental Lisp
This lisp type is characterized by the tongue protruding past the teeth during production of sounds that are typically produced with the tongue on the alveolar ridge. These sounds typically include /s/ and /z/. The resulting production is closer to a ‘th’ sound. For example, “blocks” may sound like, “blockth”. In some cases, this lisp may include tongue protrusion on other alveolar ridge placement sounds including /t, d, n, and l/. This lisp type is the most common and is considered developmental until age four and a half.
Similar to a frontal lisp, the dentalized lisp makes /s/ and /z/ production sound more like a ‘th’. However, during a dentalized lisp, the tongue presses against the front teeth instead of protruding through the teeth (as they do in an interdental lisp). This also may be considered developmental until age four and a half.
A palatal lisp is caused by the middle part of the tongue blocking forward airflow necessary to create the /s/ or /z/ sound. The middle part of the tongue may block the airflow at the hard or soft palate. This type of lisp is not considered developmental and warrants further assessment by a speech-language pathologist.
A lateral lisp occurs when the posterior lateral margins of the tongue do not seal with the top back molars while producing forward airflow sounds, such as /s/ or /z/. The result? Air escapes out the sides of the tongue instead of forward, creating a slushy-sounding fricative or affricate. This type of lisp is not considered developmental and warrants further assessment by a speech-language pathologist.
I hope that this post answered some of your questions about the various types of lisps and if you should consider reaching out to a speech-language pathologist. If you are interested in scheduling an assessment with Jennifer Katz Inc, please contact us!