What Causes a Lisp?

A Developmental Phase or Cause for Concern?

Help determine if your child’s lisp is cause for concern or a typical developmental phase he will outgrow as he gets older.

Most parents become used to their children’s speech and can understand what they're saying perfectly. But if you listen carefully, you may notice your child pronouncing certain sounds incorrectly. There are a range of speech challenges children may encounter, many of which are developmental phases that will work themselves out as the child gets older. Lisping, the inability to form certain sounds, is one commonplace type of speech disorder.

What Is a Lisp?

A lisp is a speech disorder characterized by articulation problems. It occurs when the tongue is not placed correctly in the mouth, interfering with the airflow. This can cause sounds to be distorted when a child speaks. A child with a lisp may have difficulty making the “s” and “z” sounds and replace them with the “th” sound. For example, the word “super” comes out as “thuper.”

Professionals distinguish among four types of lisps: frontal, palatal, lateral and dental. Each type is characterized by a different, incorrect placement of the tongue. In frontal lisps, also known as interdental lisps, the tongue sticks out between the front teeth and restricts the airflow. This is the most common type of lisp. A dental lisp is similar to a frontal lisp, except the tongue pushes against the front teeth, instead of protruding between them. A palatal lisp occurs when the middle of the tongue touches the roof of the mouth, toward the back. The lateral lisp is similar, with the tongue directed toward the roof of the mouth, and air flowing over the sides of the tongue.

Tongue-ties may also cause lisping. Tongue-ties occur at birth, when the frenulum, the skin beneath the tongue, attaches the bottom of the tongue to the floor of the mouth. This restricts the tongue’s movement and can affect a child’s ability to make certain speech sounds.

Which Lisps Are Developmental?

Often, a lisp is a temporary impediment that a child will outgrow. The frontal and dental lisps may occur in young children when they are beginning to talk and refining their speech skills. These lisps often disappear on their own, around age 4. Palatal and lateral lisps are not part of normal speech development, and therefore are less likely to resolve themselves on their own. Children are also unlikely to outgrow lisps caused by tongue-ties.

It can be difficult for the untrained ear to determine which type of lisp a child is exhibiting. If you are questioning your child's speech development, speak with your preschool or daycare. They may have screening devices that can be used to help determine if your child's speech development is normal for his age. For example, mispronouncing a sound like "th" is common in young children and usually not cause for alarm. You may also wish to speak to your healthcare provider, who can discuss whether speech therapy is necessary. Certainly, if your child's lisp is not improving around age 4 or if he is becoming self-conscious about his speech, visit your doctor.

Types of Treatment

A doctor's exam can determine if there are physical issues affecting your child’s speech. For example, in the case of tongue-ties that cause a lisp, a simple surgical procedure can be performed to free the tongue. Your doctor may also recommend that your child have a hearing test. A child who has difficulty hearing may also have difficulty speaking.

If you are advised to see a speech and language pathologist, this professional will carefully listen to your child’s speech and identify the specific problems with articulation. She can identify the exact type of lisp your child exhibits and determine whether it is developmental or requires treatment. If treatment is required, the speech and language pathologist will create a plan for your child that may include subsequent visits, as well as speech exercises to complete at home.

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