Types of Lisp Speech Disorders

Lisps, also referred to as Functional Speech Disorders or FMD’s, are amongst the most commonly identified and widely recognized speech problems that people experience. A “lisp” is an articulation problem that results in the inability to pronounce one or more consonant sounds. 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 four main types of lisps. Lisps can be common and normal in various stages of development in children. In some cases, lisps don’t fade as the child ages and can persist into the adult years. 

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.

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”.
  • Dentalized lisp or dentalized production – This type of lisp occurs when the tongue pushes against the front teeth. This results in a muffled s or z sound. 
  • 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. 
  • 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.

Why do People have a Lisp? Is a lisp a mental disorder?

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. 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. 

-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.

-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. 

-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. 

-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. 

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. Some specific techniques in individualized therapy might include the use of verbal, visual, or tactile cues. Verbal cues refer to the use of verbal instructions as well as demonstrating how to properly and effectively position the tongue and lips to articulate the sound. Visual clues include modeling how the sound should look and sound as well as the use of gestures to illustrate a certain sound. Tactile cues are when the therapist models the positioning and placement of the tongue and lips using touch. Other techniques that may be included in speech therapy are muscle strengthening exercises, learning to pronounce certain sounds and words, and a more general approach to annunciation coaching and support. 

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. Fill out our Get Started form to book a free introductory call and start your journey with one of our highly specialized therapists. 

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