A lisp is a functional speech disorder that involves the inability to correctly pronounce one or more sibilant consonant sounds, usually s or z .


Lisping is a speech disorder characterized by the inability to correctly pronounce the sounds of s or z , known as the sibilant consonants. Usually th sounds are substituted for the sibilants. The word "lisp," for example, would be pronounced "lithp" by someone with this speech disorder.

Many children lisp at certain stages of speech development, especially when they lose their front primary teeth. Lisping is, therefore, sometimes called a developmental phonetic disorder. Frontal or interdental lisp is produced when the tongue protrudes through the front teeth when teeth are missing and is the most familiar type of lisp. Sibilant production may be interfered with in a number of other ways as well. These are all classified as lisping and include excessive pressure by the tongue against the teeth, the tongue held too far back along the midline of the palate, and a "substitute hiss" produced in the throat or larynx.

Sometimes children with functional speech disorders have problems making other sounds, such as sh , l , r , and ch . When a child cannot produce these sounds correctly, the condition is usually not considered a true lisp, but is a functional speech disorder.

Children can have a functional speech disorder as well as a developmental phonological disorder. The latter is not a matter of being able to physically make a specific sound but is a language disorder. These children have trouble organizing the sounds of speech in common patterns and may consistently replace one sound with another. For example, a child may say "wun" instead of "sun" or "doe" instead of "so."

There are four main types of lisps.

  • Interdental lisp—occurs when the tongue protrudes between the front teeth and the s or z is pronounced like th .
  • Dentalized lisp or dentalized production—occurs when the tongue pushes against the front teeth.
  • Lateral lisp—sounds wet because the air flows around the tongue, which is in the normal position to produce the l sound.
  • Palatal lisp—the middle of the tongue touches the soft palate, or roof of the mouth, when trying to produce the s sound.


According to the National Institute on Deafness and Other Communication Disorders, about one in six people in the United States (42 million adults and children) has a communication disorder. Of them, 14 million have a speech, voice, or language disorder that is not linked to hearing loss. Functional speech disorders with no known cause, such as lisping, affect 10 percent of the population; 8–9 percent serious enough to require treatment. Nearly 5 percent of first graders have functional speech disorders, and 50–70 percent of all children with functional speech disorders struggle academically throughout elementary school and high school.

Causes and symptoms

As a functional speech disorder, lisping has no clear known cause. It is often referred to as a speech delay of unknown origin. Structural irregularities of the tongue, palate, or teeth (including abnormalities in the number or position of the teeth) may be implicated in lisping, but they generally are not the main causes. Mild hearing loss involving high frequencies may also impair a child's ability to hear language correctly and be able to repeat phonetic sounds. In some cases, a child with no physical abnormality will develop a lisp. It has been thought that some of these children may be imitating another child or an adult who lisps.

Lisping is also associated with immature development. Some children will adopt a lisp as a means of gaining attention. Other children will begin to lisp after they have experienced unusual stress or trauma. This behavior is part of a regression into a more secure period and can include other types of regressive behaviors such as bed wetting or wanting to sleep with the light on in the bedroom.

One theory of the cause of lisping is the result of tongue thrusting, a physiological behavior that causes the tongue to flatten and thrust forward during swallowing and speaking. It is suggested that thumb sucking , overuse of pacifiers, bottle feeding, and recurrent upper respiratory illnesses cause tongue thrusting. Thumbs (or fingers), artificial nipples, and pacifiers keep the tongue flat and do not allow the muscles of the tongue to develop in a normal fashion. When the child speaks, the tongue shoots forward, creating a lisp.

Frequent upper respiratory illnesses often stuff the nose, forcing these children to breathe through their mouths. The sounds that they make when they speak may be thick and garbled, and may encourage lisping. Closing the mouth and teeth to make s or z sounds cuts off the breath, so children compensate by trying to speak without closing their mouths completely. Thus, a lisp develops.

When to call the doctor

The interdental lisp and the dentalized lisp are common in normal speech development. However, if they persist well past four-and-one-half years and garble the speech so that the child is not understood, he or she should be evaluated. The evaluation will determine if there is a physiological basis for the lisp and identify the type of lisp. In some cases, the child will be evaluated and observed for several months or longer to see if the condition can be outgrown. Lateral and palatal lisps are not found in typical speech development and should be evaluated by a speech-language pathologist. If untreated, lisping can persist into adulthood.

For some children, everything they say seems to be interdental. In these cases, there may be an obstruction of the nose because of infection, allergy, enlarged adenoids, or other facial problems. Excessive interdental speech can also be related to mouth breathing and sucking habits. These children should be seen by a physician to treat the health problems and then referred to a speech-language pathologist to correct the lisp.


A physician can determine whether there are structural irregularities within the mouth or problems with the child's hearing, and can treat related allergies and nasal problems. However, true assessment of a child's ability to make speech sounds must be done by a speech-language pathologist. The child's medical history will be taken and the speech-language pathologist will examine the anatomy of the child's mouth and the movements it can make. Next, the child's speech and reading aloud is often recorded for later analysis. This speech sample will also yield information about the quality of the child's voice, how fluent speech occurs, and the child's semantic and physical sound-making skill.


Typical treatment is called articulation therapy. The speech-language pathologist finds out whether the child can hear proper speech sounds, and proceeds to read a list of words with specific sounds that the child is having trouble articulating. Lists of contrast words are also read so that the child can hear the subtle differences in word sounds. Therapy then moves to working on the position in the word where the sound occurs; that is, at the beginning, in the middle, or at the end. Specific word exercises follow, beginning with single sounds, then syllables, and moving on to words, phrases, and sentences. Finally, the child participates in controlled conversations such as talking casually during a meal.


Most lisps are developmental and resolve themselves in children by the time they are about five to eight years old. If they last longer or are of a specific type, speech therapy is recommended. The outcome of speech therapy is usually quite good. Depending on the specifics of the therapy and the nature of the lisp, treatment can be relatively short term, lasting only a few months. Some cases may take a year or more.


Parents can reduce the risk of a lisp developing because of tongue thrusting by restricting pacifier use or choosing to breastfeed their babies. They can also speak clearly in complete sentences around their children and not use baby talk. They should treat allergies and respiratory illnesses immediately to keep the nose open and breathing free. The child's hearing and teeth should be checked periodically to make sure he or she can hear speech clearly and form words correctly. Parents can also encourage the musculature of the mouth by showing children how to drink from straws and how to blow bubbles. In addition, playing word and naming games encourages good speech development and stimulates learning.

Parental concerns

In many families, a child's lisp goes unnoticed, especially if it does not interfere with understanding what the child is saying. These children may grow up content to keep a lisp, feeling that it is a specific part of what makes them who they are, just as some people keep a gap between their front teeth and see it as distinct characteristic. (Lauren Hutton kept the gap between her teeth even as she became a top model, and Boris Karloff had one of the most famous lisps in the world.)

Outside of the home, some children may be teased by other children or feel embarrassed to speak up in the classroom. They may have trouble spelling or even reading because they cannot make some of the sounds necessary to read and write well. These children may have serious self-esteem issues related to their lisps. In these cases, seeing a speech-language pathologist early in their lives and correcting their lisps could bolster self-confidence and ability to learn.

Still other families may think that a child's lisp is endearing and cute. They may even encourage the child to continue lisping because he or she receives positive regard whenever the lisping sounds are made. Sometimes, these same families suddenly decide that lisping is no longer cute and want their children to drop their lisps and grow up. These children still can benefit from speech therapy, but they may become resistant to treatment because they are confused about the abrupt change in the family's behavior. In this case, counseling is recommended in addition to sessions with a speech-language pathologist.

A lisp can be a source of distress for adolescent boys and young men who may be told that they are gay because they lisp. A functional speech disorder has no connection with a person's sexual orientation. Many young men, although they fear it may be too late, seek out speech-language pathologists as adults to correct their lisps because of this teasing.


Palate —The roof of the mouth.

Tongue thrusting —A physiological behavior that causes the tongue to flatten and thrust forward during swallowing and speaking.



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American Speech-Language-Hearing Association 10801 Rockville Pike Rockville, MD 20785. (301) 897-5700. Web site:

Council for Exceptional Children. Division for Children with Communication Disorders. 1920 Association Drive Reston, VA 22091. (703) 620-3660.

National Institute on Deafness and Other Communication Disorders National Institutes of Health. 31 Center Drive, MSC 2320 Bethesda, MD 20892-2320.

Janie Franz

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