Speech sound errors are common as individuals learn to produce their native language. A lisp is frequently encountered, particularly in developing speakers. Understanding if a lisp is a temporary developmental phase or a persistent speech pattern helps clarify concerns and recognize when professional guidance might be beneficial.
What is a Frontal Lisp?
A frontal lisp, also known as an interdental lisp, occurs when the tongue protrudes forward between the front teeth during “s” and “z” sounds. This results in these sounds being replaced by a “th” sound, as in “yeth” instead of “yes” or “thun” instead of “sun”. Air flows out the front of the mouth, over the tongue, instead of through a narrow channel behind the teeth.
Other lisp types include a lateral lisp, where air escapes over the sides of the tongue, producing a “wet” or “slushy” sound. A dental lisp involves the tongue pressing against the back of the front teeth, muffling the sound. Recognizing these differences helps identify the specific speech pattern.
Normal Speech Sound Development
Learning to produce speech sounds is a gradual process. The “s” and “z” sounds, affected by a frontal lisp, are generally acquired later. Most children produce these sounds correctly by 4 to 5 years of age.
A frontal lisp is common and normal in younger children. This occurs as they learn precise tongue movements and coordination. Therefore, a frontal lisp in a child under 4.5 or 5 years is often a temporary phase as their speech system matures.
When a Lisp Persists
While a frontal lisp can be typical in early speech development, it usually resolves as a child gains control over oral motor skills. A frontal lisp moves beyond the typical developmental phase if it persists past certain age benchmarks.
If a lisp continues beyond 4.5 to 5 years, it warrants closer attention. Waiting too long can make correction more challenging, as incorrect tongue placement can become a habit. If a lisp affects a child’s intelligibility or confidence, professional evaluation may be beneficial.
Understanding the Causes of Lisps
The persistence of a frontal lisp beyond the typical developmental window can be linked to several factors. Oral motor habits, such as a tongue thrust where the tongue pushes forward excessively during speech or at rest, are common causes.
Other habits like prolonged thumb sucking or extended pacifier use can influence tongue placement. Structural differences, such as a tongue tie or dental issues like misaligned teeth, can also play a role. Neurological conditions, muscle weakness, or injuries to the tongue or teeth can also contribute.
Next Steps for Persistent Lisps
If there is concern about a persistent frontal lisp, seeking guidance from a speech-language pathologist (SLP) is a next step. An SLP evaluates and addresses speech sound disorders.
During an assessment, the SLP evaluates the lisp’s type and severity. This involves examining mouth anatomy and tongue placement during speech. The SLP assesses “s” and “z” sounds in various contexts and evaluates oral motor skills. This evaluation helps identify underlying causes and determine if intervention is recommended.