A lisp is a common speech impediment that affects the production of sibilant sounds, most notably the /s/ and /z/ sounds. The difficulty arises from incorrect tongue placement during sound production, which distorts the airflow necessary for a crisp sound. While some lisps are part of typical speech development in young children, the lateral lisp is a specific type that rarely self-corrects and often requires targeted intervention.
Understanding the Characteristics of a Lateral Lisp
The defining characteristic of a lateral lisp is the misdirection of airflow during speech. Normally, the air stream is channeled precisely down the center of the tongue to create the characteristic “hissing” sound. With a lateral lisp, the sides, or lateral margins, fail to raise high enough to seal against the upper back teeth.
This failure allows the air to escape over the lateral edges of the tongue and into the cheeks. The auditory result is often described as a “slushy,” “mushy,” or “wet” sound because the air is dispersed rather than centrally focused. This contrasts with a frontal lisp, where the tongue protrudes between the front teeth, causing the sound to resemble a “th.” A lateral lisp is not considered part of typical speech development and usually requires speech therapy intervention.
The Role of a Speech-Language Pathologist
A lateral lisp is challenging to correct because it involves retraining a deeply ingrained motor pattern and muscle coordination. A Speech-Language Pathologist (SLP) is the professional best equipped to assess and treat this articulation disorder. The SLP’s role begins with a thorough diagnostic evaluation, including a case history, an oral-motor examination, and an articulation test to confirm the lisp type and severity.
This assessment identifies underlying contributing factors, such as poor tongue muscle coordination, a habitual tongue thrust, or structural elements like dental alignment. Based on this information, the SLP develops an individualized treatment plan to establish a new, correct motor plan. Since lateral lisps are not typically outgrown, intervention can begin in preschool or early school-age years, though therapy is also effective for adults.
The SLP guides the client through a hierarchy of practice, starting with the target sound in isolation, then moving to syllables, words, phrases, and conversational speech. They provide tactile, visual, and auditory cues necessary for the client to achieve the correct tongue placement. This structured approach ensures the client learns the precise physiological movements required for accurate central airflow.
Specific Therapeutic Techniques for Correction
The core of lateral lisp therapy involves teaching the client to redirect the airflow from the sides to the center of the mouth. One effective technique is sound shaping, where the SLP uses a sound the client can already produce correctly to elicit the target sound. The “exploding T” technique is a common example: the client repeats the /t/ sound rapidly and holds out the final repetition, which shifts the airflow into a central /s/ sound.
Another technique utilizes facilitative contexts by starting with sounds that require a sealed tongue position. For instance, saying the vowel /i/ (as in “see”) helps anchor the sides of the tongue against the molars, which can then transition into a correct /s/ production. The SLP also employs tactile cues to provide physical feedback, sometimes using tools like a tongue depressor or a straw to guide central airflow.
Visual feedback, often involving mirrors, allows the client to monitor tongue placement. SLPs also use auditory discrimination, where the client learns to distinguish between their incorrect, slushy production and the correct target sound. These methods focus on creating a new, habitual motor pattern by providing immediate, multi-sensory feedback on tongue placement and air direction.
Practice Activities and Exercises at Home
Home practice is a necessary supplement to clinical sessions, serving to reinforce the correct motor patterns established with the SLP and help generalize the sound into everyday speech. These exercises must be consistent and structured, always using the specific cues and techniques provided by the therapist. The goal of home practice is to achieve a high number of correct repetitions, transforming the new movement into a natural, unconscious habit.
Practice progresses through several stages:
- Practicing sound production in isolation, such as using the “exploding T” technique repeatedly until the correct /s/ is consistently produced without the lateral airflow.
- Word-level practice, often utilizing minimal pairs (words that differ by only one sound, such as “sun” and “thumb”) to highlight the contrast between the correct and incorrect sounds.
- Reading aloud drills, focusing on words and sentences containing the target sound to build automaticity and fluency with the new articulation pattern.
- Carryover activities, where the client consciously monitors and uses the correct sound in casual conversation.