Types of Lisp Speech Disorders
The most common example of this is the inability or difficulty pronouncing the letter sounds “s” or “z”. This is most often due to incorrect placement of the tongue within the mouth and is called an interdental lisp. However, this is just one of the four main types.
Lisps can be common and normal in various stages of speech development in children. In some cases, lisps don’t fade as the child ages and can persist into the adult years.
To better understand what a lisp is, it’s helpful to know how precise tongue placement and airflow work together to create clear /s/ and /z/ sounds, and why variations in these patterns lead to different types of lisps.
Many families also ask “what causes lisps?” and “when should a lisp be corrected?”. These are questions that speech-language pathologists address through careful evaluation and early intervention.
In this article, we will explore the different types of lisps, their causes, and how they can be effectively treated and often eventually corrected through treatment with a specialized Speech Therapist. We will also offer examples of words that can be difficult for people who struggle with lisping, as well as practical activities you can try at home to support clearer speech.
We will not be digging deep into sudden-onset lisps. There are many reasons why an adult might develop a lisp, but any lisp that appears suddenly is cause for concern, and the individual should seek the care of a medical professional as soon as possible. To read further into this topic, check out our blog post Why am I Suddenly Talking with a Lisp?
What are the different kinds of lisps?
There are many different types of lisps; however, there are four types that are most commonly observed. They are:
Interdental lisp – Interdental lisp is the most common and well-known type of lisp. It is caused by the tongue pushing forward between the front teeth. In the case of an interdental lisp, the s or z sound is pronounced like “th”. This is the type that most parents notice first because the sound substitutions are easy to hear. Interdental lisps are sometimes typical in very young children, but speech therapy is recommended if they persist past age 4-5.
Dentalized lisp or dentalized production – This type of lisp occurs when the tongue pushes against the front teeth. This results in a muffled sounding s or z sound rather than a true substitution. Speech therapy for this type of lisp typically focuses on retraining tongue placement just behind the teeth.
Lateral lisp – A lateral lisp occurs when air exits the mouth out of the sides, resulting in slushy or wet-sounding speech as the spoken sound mixes with the sound of air and saliva. This type of lisp is most famously depicted by cartoon characters such as Sylvester the Cat and Daffy Duck. Lateral lisps are not considered developmentally normal at any age, and they generally require targeted speech therapy to correct. This type of lisp also tends to be harder to correct without help from a speech therapist because it's due to airflow escaping in the wrong direction.
Palatal lisp – This type of lisp is less common and occurs when the center of the tongue is in contact with the roof of the mouth, or the soft palate, when attempting to produce the s sound. This results in a dull or distorted quality of speech. Early evaluation is recommended because addressing the tongue’s back positioning early often leads to faster progress.
Why do people have a lisp?
Like other functional speech disorders, the cause of lisps isn’t always known. In these cases, a lisp would be classified as a speech delay or disorder with an unknown origin.
It is incredibly important to note that lisps are not a mental disorder. They relate to speech-sound production, which is mechanical and motor-based rather than cognitive or psychological.
Some of the known causes or factors in lisp development are:
Phonetic vs Linguistic
- When it comes to lisps, the cause is almost always a phonetic disorder, meaning the affected person struggles to position the tongue, lips, teeth, and jaw correctly to achieve the attempted sound. This differentiates lisps from other speech disorders, which are linguistic in origin, meaning the intended sounds can be achieved, but the person struggles with knowing and identifying which sound to use, especially when they are similar to others in sound or meaning. Lisps almost always fall in the phonetic category, and their treatment focuses on motor learning rather than language concepts.
Physiological factors
- In some cases, there are structural or physiological factors that contribute to the cause of a lisp. These can include abnormalities or irregularities with the soft palate, tongue, teeth, or position of teeth. While these things can be factors in lisp development, they are usually not the main or root cause. Speech therapy is still effective with appropriate modifications.
Genetics
- Genetics can play a significant role in the development, structure, and position of one’s jaw, teeth, tongue, and bite. In some cases, a lisp can be caused by abnormal development or positioning of the jaw and/or teeth. A family history of articulation difficulties also increases the likelihood of a child developing a lisp.
Tongue Thrust/ Orofacial Myofunctional Disorder
- Tongue thrust or OMD refers to the reflex of pushing the tongue forward between the front teeth. This reflex is normal in babies and children, and in most cases, children’s speaking and swallowing patterns evolve and develop normally. By the age of 6, most children no longer have a tongue thrust reflex. In some cases, prolonged tongue thrust is related to extended use of pacifiers, baby bottles, or other habits such as thumb sucking, allergies, or an untreated tongue-tie. Treatment may involve both myofunctional exercises as well as articulation exercises because tongue thrust often overlaps with interdental lisps.
Hearing Loss
- Some lisps are related to mild hearing loss, particularly involving high frequencies, which can affect the person’s ability to hear sounds correctly, and subsequently, they will struggle to repeat them. Children with frequent ear infections may also struggle with inconsistent sound production and lisps due to their fluctuating hearing.
What are some words that are hard to say if you have a lisp?
/s/ and /z/ are the sounds that many people with lisps struggle to pronounce. Individuals with a lisp may struggle to say the following words:
- Sun
- Snake
- Sister
- Spaceship
- Pizza
- Glasses
- Busy
- Music
- Desserts
- Fastest
- Science
- Frozen
- Lisp
How are Lisps Treated? Can a Lisp be Corrected?
Speech Therapy can be incredibly effective when it comes to addressing pronunciation and articulation concerns, such as lisping. Speech Therapy to improve a lisp typically involves a progression of skill development, working first to clearly say the challenging sounds on their own (s and z, for example) and then, over time, working to properly execute these sounds within various words and combinations of words. How long this process takes and what the steps between each goal look like will vary from person to person.
Speech Therapy will aim to bring awareness to the various challenges and areas in need of improvement and to help bring mindfulness to related goals and positive outcomes. This is referred to as Articulation Therapy.
Speech therapy for lisps often includes:
- Exercises to practice proper tongue placement
- Auditory discrimination practice to help the individual hear correct vs. incorrect speech sounds
- Including mirrors or digital tools for visual feedback
- Myofunctional exercises in cases where tongue thrust patterns are present
- Progressive practice from sounds - syllables - words - sentences - conversation
Many families ask, “Does speech therapy help with lisps?”. The answer is simple - yes! Evidence strongly supports speech therapy for both children and adults, especially when started early.
Activities to Try at Home to Help with a Lisp
There are activities that can be done at home to help reinforce what is learned in therapy. Some of these include:
- Practicing “snake sounds” (/s/)
- Using a mirror for visual feedback on tongue placement
- Straw sucking activities to encourage forward airflow
- Reading /s/ and /z/ heavy books together
- Gently reminding the tongue to stay behind the teeth
- Playing listening games to hear correct vs. incorrect speech sounds
If you or your loved one is struggling to identify or correct a lisp, connecting with a speech therapist can be an incredibly helpful and effective first step. Book a free introductory call and start your journey with one of our highly specialized therapists.
If you are looking for more information, we have many other blogs on the topic of lisps.