What Is a Lisp? The 4 Types, Causes, and How to Correct Them
Leanne Sherred, M.S., CCC-SLP
A lisp is a speech sound disorder that affects how a person pronounces the /s/ and /z/ sounds, caused by incorrect tongue placement in the mouth.
There are four types of lisps: interdental, dentalized, lateral, and palatal. All of them can be corrected at any age with speech therapy.
Key takeaways
The most common type of lisp is the interdental lisp, where the tongue sticks out between the front teeth and /s/ sounds like [th]. For example, "sun" sounds like "thun."
A lisp is caused by incorrect tongue placement during speech. It can be linked to tongue thrust, tongue tie, or jaw alignment differences.
Most children and adults can correct a lisp through speech therapy that teaches proper tongue placement, airflow control, and new speech habits. Starting before age 8 typically leads to faster progress for children.
Trying to fix a lisp at home without guidance can reinforce incorrect habits. Working with a licensed speech therapist is the most effective approach.
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Get startedWhat is a lisp?
A lisp means difficulty pronouncing the /s/ or /z/ sounds. This is because of an incorrect motor pattern of tongue positioning.
When a person has a lisp, they position their tongue in a way that blocks or distorts the airflow needed to make the /s/ and /z/ sounds. This distortion of airflow creates the lisping sound we are familiar with.
Lisps are one of the most common speech issues in both children and adults.
The 4 types of lisps and examples of each
Interdental lisp
An interdental lisp, sometimes called a frontal lisp, is the most common type of lisp. This is where a [th] sound is produced instead of an /s/ or /z/ sound. With an interdental lisp, a word like “sing” may be pronounced as “thing,” and a word like “zebra” may be pronounced as “thebra.”
“It's called an interdental lisp because the tongue is placed incorrectly in the speaker’s mouth, often protruding between the front teeth,” says Abby Barnes, M.S., CCC-SLP, a speech-language pathologist at Expressable.
An interdental lisp is developmentally normal until around age 4½. Most children naturally outgrow it by then.
Dentalized lisp
A dentalized lisp is similar to the interdental lisp. While the tongue doesn’t completely protrude between the front teeth, it does push against the back of the front teeth, directing airflow forward. This can cause a muffled sound when speaking.
Lateral lisp
A lateral lisp makes a very distinguishable sound once you know what to listen for. In this type of lisp, the tongue stays in a relatively correct position. However, the sides of the tongue are raised enough to cause air to escape from either side of the mouth. All of this extra air causes the speaker to sound “slushy,” and speech takes on a uniquely “wet” or “spitty” characteristic. In fact, you may even hear a lateral lisp called the “slushy lisp.”
Palatal lisp
A palatal lisp occurs when the tongue raises up and touches the roof of the mouth, also called the soft palate. While this type of lisp is not as common, it can make it hard to pronounce the /s/ and /z/ sounds.
Words with a lisp
For people with a lisp, words that have an /s/ or /z/ sound in the beginning, middle, or final positions of the word are tricky to pronounce. Below you’ll find a list of some hard words to say with a lisp.
Keep in mind, this is the case with any word that has an /s/ or /z/ sound. The lisp words below aren’t inherently different or special; they simply include an /s/ or /z/ sound.
/s/ words that can be hard to say with a lisp
Sun
Sit
Sand
Sick
Scissors
Baseball
Grasshopper
Glasses
Bus
Face
This
Class
/z/ words that can be hard to say with a lisp
Zebra
Zero
Zinc
Zip
Lazy
Closet
Music
Thursday
Cheese
Cookies
Nose
Fingers
All four lisp types can affect any of these types of words. The difference is that each speech production would sound a little different based on the type of lisp someone has.
Let’s take the word “sun” for a lisp example:
With an interdental lisp, it would sound like “thun.”
For someone with a dentalized lisp, it would sound similar to “thun” but with less airflow.
With a lateral lisp, “sun” would sound wet and slushy. The first sound would be somewhere between an /s/ and “TH” sound, but with lots of air coming over the sides of the tongue.
A palatal lisp would have the /s/ sound sounding more like a soft “SH,” similar to “shun.”
What causes a lisp?
The reason for the incorrect tongue positioning that causes a lisp isn’t always clear. Lisp causes can include a variety of factors, including:
Learning to produce the /s/ and /z/ sounds incorrectly as a child
A jaw misalignment, or problems with a person’s jaw alignment
A tongue tie, which occurs when the tongue is attached to the bottom of the mouth and its movement is limited; this may lead to a lateral lisp
A tongue thrust, in which the tongue protrudes forward; this can also impact feeding and swallowing
Learn more about the causes of lisps and whether they're genetic.
A lisp makes it difficult to pronounce the /s/ and /z/ sounds. Learn what causes lisps in children and adults—including whether they're genetic.
How can a lisp affect a person’s life?
Lisping often doesn’t have a severe impact on a person’s ability to be understood. However, a lisp can still affect a person’s social and emotional wellbeing.
Some caregivers fear their child could be teased by their peers. Children with a lisp may feel anxious or uncomfortable when speaking with other people. This can affect their confidence, self-esteem, and ability to socialize with others.
For adults with a lisp, these effects can be worse. They may feel frustrated or embarrassed when speaking at work. They may try to avoid certain social situations altogether.
Lisps affect everyone differently, and not everyone wants to fix a lisp. However, there are things that parents and adults can do to minimize the impact of a lisp.
Is it possible to get rid of a lisp?
Yes, you can get rid of a lisp at any age with the help of speech therapy. A speech-language pathologist, also known as a speech therapist, can identify what kind of lisp you have, then teach you how to change your tongue placement and control your airflow so you can produce sounds more clearly.
“Therapy often includes targeted exercises, step-by-step practice, and lots of repetition to help build new speech habits,” says Barnes. With consistent practice, most people make great improvements, often faster than they expect. It’s never too late to strengthen your speech skills and boost your confidence.
Claudia's story
With online speech therapy, Claudia got rid of a lisp she'd had since childhood--and learned to communicate with more confidence.
Read Claudia's storyHow are lisps recognized and diagnosed?
In most cases, your child’s pediatrician, school nurse, or teacher may refer you to a speech therapist. Speech therapists are communication experts and are the most qualified professionals to assess, evaluate, and treat people with lisps.
As mentioned, there are different types of lisps of varying severities. If you suspect your child has a lisp, it’s a good idea to seek an evaluation from a speech therapist.
At Expressable, your speech therapist may do the following during an evaluation for a lisp:
Review your or your child’s medical history
Examine the anatomy of the mouth and tongue placement
Check for issues like a tongue tie or tongue thrust
Observe your or your child’s speech fluency, vocal quality, and social communication skills
Determine whether a lisp or a different type of speech sound disorder is present
Provide a professional opinion of when to start intervention; for example, they may recommend delaying treatment and monitoring your child to see if the lisp naturally disappears over time
How to correct a lisp
If you’re ready to work on fixing a lisp, the tips and exercises below can help you get started at home. However, keep in mind that working with a speech therapist is the best way to get rid of a lisp. In lisp speech therapy, you will learn to say the /s/ sound correctly at various levels, in a specific order, so you can achieve success. Practicing a sound incorrectly, at a higher level than you’re ready for, can cause you to form an incorrect motor pattern. You would then need to “unlearn” that motor pattern in order to say the sound correctly.
To avoid worsening the lisp or causing new problems, having a speech therapist guiding this process is your best bet!
Tips for correcting an interdental lisp
Since interdental lisps are caused by incorrect tongue placement, they’re easy to visualize. This can be helpful when trying to correct this type of lisp. For example, when looking in a mirror, it’s often easy to see the tongue protruding between the two front teeth. If you or your child is trying to fix an interdental lisp, use this to your advantage and practice in front of a mirror!
The tongue should go behind the front teeth. It should barely touch the “bumpy part” of the mouth right behind your teeth, called the alveolar ridge. When the tongue is in the correct position and you begin to push air gently out, the air should flow smoothly right over the tongue and out the front of your mouth.
For quick practice, work with your child in front of the mirror. Watch closely how their teeth and mouth move when saying the /s/ or /z/ sound.
If your child has an interdental lisp, show them the correct tongue placement yourself. See if they can imitate your mouth movements. This can be helpful for anyone, especially those of us who are more visual learners.
Tips for correcting a lateral lisp
If you think that you or your child has a lateral lisp, you can once again try practicing the exploding /t/ technique. This will help position the tongue correctly so that airflow is directed out of the front of the mouth.
You can also use a straw and hold it in front of the teeth. Try to make the air come through the straw instead of out the sides of the tongue. You’ll quickly notice the difference, as the sound varies considerably depending on where the airflow is directed. This activity also provides quick feedback so that the speaker can continue working on their /s/ or /z/ productions.
Some mild lisps improve with home exercises. But persistent lisps—especially in adults—respond best to speech therapy. Here’s what actually works.
Tips for correcting a dentalized lisp
To help fix a dentalized lisp, focus on making the tongue only lightly touch behind the front teeth, instead of pushing hard against them.
One simple exercise for a dentalized lisp is called the exploding /t/ technique. To begin, say the /t/ sound four times in a row, and then hold the sound on the last one. It will go something like: t-t-t-tsssssss. The /t/ will automatically turn into an /s/ sound. Pretty cool, huh? Try another with just one exploding /t/: t-ssss.
Then, try to produce the /s/ sound while maintaining that same placement. It will sound correct because the tongue is now in the correct position.
Tips for correcting a palatal lisp
In order to fix this type of lisp, it's important to review appropriate tongue placement.
You may also need to focus on lowering the tongue slightly so that the body of the tongue is not raised as high when speaking.
It's common for a person with a palatal lisp to keep their mouth slightly open when making the /s/ or /z/ sound. If so, have them watch their tongue placement in the mirror. Model correct tongue placement, so that the tip of the tongue only touches slightly behind the teeth, and the body of the tongue is positioned lower in the mouth instead of touching the palate.
When should a lisp be corrected?
There are a few things to think about before deciding if it’s time to correct an /s/ or /z/ sound.
1 How old is the person with the lisp?
When children first begin talking, often around the age of 2, lisps can start to become noticeable. Kids can learn to make the /s/ sound clearly anytime between ages 3 and 8. However, it’s a good idea to start working on this sound before age 8. If a child is able to make an /s/ sound that's close to correct, it's a safe bet that they're ready to begin practicing this sound in speech therapy.
Remember that a lisp can be corrected in adults, too. It’s never too late!
2 What type of lisp does the person have?
Dentalized and interdental lisps are relatively common and normal in young children. Many children have this kind of lisp up to around 4½ years of age. Lateral and palatal lisps, however, do not occur as a normal part of speech development.
Either way, it’s a good idea to talk with a speech therapist, who can evaluate and identify the type of lisp that you or your child may have. They can provide a clinical recommendation on how best to correct the lisp.
3 Is the lisp affecting the person’s confidence or self-esteem?
“Lisping affects everyone differently, and not everyone wants to change the way they speak,” Barnes says. However, speech sound differences that affect how clearly a person speaks may impact their confidence, self-esteem, and willingness to participate and socialize with others.
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Get startedHow long does it take to correct a lisp?
Every person is different, and the frequency and intensity of speech therapy will shift depending on their needs. Some children can see big improvement in a month or two. Others will need speech therapy for a year or more. In most cases, the recommended frequency for lisp speech therapy is two sessions per week.
Factors that can affect the length of treatment include:
The person’s age
Type of lisp
The person’s awareness of mispronunciations and ability to self-correct
How well they follow directions
How often they practice at home
Find a speech therapist for a lisp
If you think that you or your child have a lisp, or you notice your child struggling with their /s/ and /z/ sounds with little improvement over time, contact a speech therapist. Their professional guidance will help you make the most informed treatment decision.
At Expressable, we’re here to listen to your speech concerns and guide you on next steps. We can match you with a licensed speech therapist who can perform an evaluation and develop a treatment plan. Get in touch with us here!
Frequently asked questions (FAQs)
A lisp specifically affects the /s/ and /z/ sounds. If those sounds come out as [th], sound wet or slushy, or feel muffled, you likely have a lisp. The easiest way to check is to record yourself saying words like “sun,” “zip,” and “sister,” then listen back. If you're unsure, a speech therapist can identify the exact type of lisp and whether treatment makes sense for you.
A lisp typically affects the /s/ and /z/ sounds, since these sounds rely on precise airflow and tongue placement. However, if the tongue positioning pattern is more severe, it can sometimes affect other sounds as well. A speech therapist can help determine the full impact.
A lisp is not a form of autism. A lisp is a speech production issue related to tongue placement and airflow. Autism is a neurological developmental condition. While autistic people may also have speech differences, a lisp on its own is not a sign of autism.
Dentalized and interdental lisps are relatively common in young children. Many children have these kinds of lisps up to around 4½ years of age, and then it goes away. Lateral and palatal lisps, however, do not occur as a normal part of speech development. A speech evaluation will determine what type of lisp your child has and whether speech therapy is recommended.
Adults may have a lisp for several reasons, including incorrect tongue placement learned in childhood, a history of tongue thrust, a tongue tie, or jaw alignment differences. Some adults simply never received treatment as children. If a lisp is affecting your clarity or confidence, consider contacting a speech therapist for an evaluation to explore your options.
Some mild interdental lisps can improve with focused practice and visual feedback, like watching tongue placement in a mirror or trying the “exploding /t/” technique. However, many people need speech therapy in order to change long-standing speech habits.
Coverage depends on your insurance plan and whether the lisp is considered medically necessary. For children, especially when a lisp affects speech clarity or development, coverage is more common. For adults seeking treatment mainly for cosmetic or confidence reasons, some plans may not cover it. It's best to call your insurer directly or speak with a speech therapy provider who can help verify your benefits.
How Expressable Can Help
Concerned your child isn't reaching age-expected milestones? Looking for communication support from a professional? Expressable is a national online speech and occupational therapy practice serving children and adults. We treat all major areas of communication, feeding, and developmental skills, offer flexible hours including evenings and weekends, and accept most major health insurance plans. We’re proud to have earned more than 4,500 5-star reviews from our clients (4.83/5 average).
Our therapy model is centered on parent and caregiver involvement. Research proves that empowering caregivers to participate in their loved one’s therapy leads to better outcomes. That’s why we combine live, 1-on-1 speech and occupational therapy with personalized education and home practice activities for faster progress.
