How speech pathology can treat a lisp

A lisp is one of the most common speech problems we work with in speech pathology.

What is a lisp?

A ‘lisp’ is a term often used to describe difficult making clear, easy-to-understand ‘s’ and ‘z’ sounds. This may or may not also include the tongue poking out.
Lisps are a common type of ‘functional’ speech disorder (FSD)[1]. In other words, a difficulty making one or several specific speech sounds.  It is ‘functional’ because the root cause of the disorder is not entirely clear. These can persist into the teenage or adult years. However, they can be successfully treated with speech therapy.

What causes lisps?

Speech Sound Development

A lisp most likely has a phonetic origin. This means a child has difficulty physically achieving the correct placement of their lips, tongue, and/or jaw. Which results in errors when saying clear, easy-to-understand speech sounds. Fortunately, this does not mean we cannot fix it.
This is different from other types of speech sound disorders that have a linguistic origin. Which occurs when a child can make individual speech sounds. But is still learning to tell the difference between two sounds (e.g. run – wun). These types of speech sound errors are phonological disorders (linguistic in origin).
It is not uncommon for a child to have both a functional speech sound disorder and a phonological speech sound disorder.

Physiological Factors

There may also be physiological factors contributing to a lisp. Ear Nose and Throat specialists are unable to rule out the impact of enlarged tonsils or nasal obstructions (snuffly breathers or children with allergies) towards a lisp. The reasoning behind this is that enlarged tonsils take up much of the space at the back of the throat. Typically, this is where the base of the tongue would normally sit. This results in pushing the tongue into a more forward position. As a result, this can often be associated with ‘mouth breathing’. Where the mouth may rest open rather than closed. The same is true for children with nasal allergies. Who may compensate by being mouth-breathers? These children do appear to dribble more frequently. This may be due to them swallowing their saliva less often.
Orthodontists and Dentists agree that genetics plays a large role in the shape of your jaw and bite. However, the shaping of the jaw and subsequently the teeth positioning is also strongly influenced by the forces of your tongue and lips and cheeks. So, a ‘tongue thrust’ where your tongue pushes forward slightly on swallowing can contribute to an ‘overbite’. Where the top teeth are pushed further forward in relation to the lower teeth. In these children and adults, we often also see ‘lisp’ speech behaviours. However, we have to treat the underlying tongue thrust behaviours first.
There are four types of lisp: interdental, lateral, palatal and dentalised.”

What does a lisp look like?

There are four types of lisp: interdental, lateral, palatal, and dentalised. The most common lisp is the interdental lisp. Firstly, an interdental lisp occurs when a child tries to say “s” and/or “z” speech sounds with the tongue sticking out between the teeth. This results in a “th” speech sound instead of an “s” or “z” speech sound.
Secondly, the dentalised lisp. This occurs when a child pushes the tip of their tongue up against their front teeth. Therefore, resulting in a muffled “s” or “z” speech sound.
A lateral lisp occurs when air is directed over the sides of the tongue instead of down the middle. For this reason, air flows over the tip of the tongue on “s” and/or “z” speech sounds. This results in a slushy “s” or “z” speech sound. A lateral lisp is not an expected error in typically developing speech.
By comparison, the palatal lisp is less common than other lisp types. A palatal lisp occurs when a child tries to say “s” and/or “z” speech sounds with the tongue touching the soft palate (the roof of the mouth).

When to seek help

Interdental lisps are common among children learning to talk. Both interdental and dentalised lisps can be a normal part of a child’s speech development, and resolve as the child matures. However, if you think your child has an interdental or dentalised lisp, and they are 4 ½ years of age or older, we recommend you contact us at Talkshop Speech Pathology.

In contrast to interdental and dentalised lisps, lateral and palatal lisps are not considered to be a normal part of a child’s speech development. If you think your child has a lateral or palatal lisp, and they are 4 years of age or older, we recommend you contact us at Talkshop Speech Pathology[5].

Adults with Lisp

Lisps can persist into adulthood. In the event that an adult did not attend speech pathology as a child. Likewise, if they discontinued speech pathology prematurely, therapy gains are often not maintained.
Some adults are not worried about having a lisp. Some adults may even see having a lisp as being a positive part of their identity. In this case, there is no need to attend speech pathology. Other adults may feel embarrassed, frustrated, or simply annoyed about having a lisp. If you feel this way, it is probably a good idea to contact us at Talkshop Speech Pathology. It is not too late for us to help you out!
“Interdental and dentalised lisps can be a normal part of a child’s speech development, and resolve as the child matures. Lateral or palatal lisps are not part of normal speech development.”

How we can help


Assessment for a lisp at Talkshop involves formal and informal speech sound assessment. In addition, we measure pre-literacy skills. Because research shows, a speech sound disorder places a child at risk for future literacy difficulties. Furthermore, assessment involves an oromotor assessment. This means reviewing the structure and function of your child’s lips, tongue, mouth, and jaw. Thereby ensuring that they have the physical ability to create clear speech sounds. Finally, we complete an informal assessment of your child’s language skills.

Lisp Therapy

Targeting Lisps
Therapy for lisps involves teaching a hierarchy of skills. In most cases, we first begin with your child saying the “s” sound by itself. The therapy ends when your child is using the new “s” independently in everyday conversation. The steps in between vary according to your child’s strengths and areas for development. As do the techniques used to help your child understand how to make their new sound in different places in a word. For example, some techniques used include:
  • visual cues (e.g. using gestures to represent speech sounds)
  • verbal cues (e.g. modeling how the speech sound sounds, providing verbal instructions)
  • tactile cues (e.g. showing the child where to place their lips/tongue/jaw).
Targeting Tongue Thrusts
Therapy for tongue thrusts also involves teaching a hierarchy of skills. A tongue thrust is a habit (the pattern of movement our brain instructs our muscles to move in). Therefore, requires a period of therapy to out-train the old habitual way of using the tongue for speech and swallowing. The way that your child uses their tongue for swallowing will need to be targeted before their interdental lisp can be targeted.
Parent Training
We always provide parent training within therapy sessions. This is so that you feel confident completing home practice tasks with your child each week. This is a high priority for us as we know that frequency of practice is so important for your child’s progress.
Last but not least, therapy involves finding the right balance of challenging and fun to keep you and your child motivated.
If you are unsure if your child has a lisp, book a free initial consultation to talk with one of our Speech Pathologists.

Read more about how Talkshop Speech Pathology treats speech delays and speech disorders

“We always provide parent training within therapy sessions”

Our FREE Discovery Session is ideal for anyone with any questions relating to speech, stuttering, language, literacy, social skills, swallowing, and voice.

This is an opportunity for us to give some information on how to monitor your concern and give you advice on how to start self-managing any issues immediately.

Discovery Sessions can help you understand if an assessment or therapy is needed, how Speech Therapy would work, and if appropriate, help you book in.


1 “speech-language therapy – Caroline Bowen.” 23 Nov. 2011, Accessed 14 Jan. 2019.

“Tonsils, Adenoids, tongue tie | ENT Specialists.” Accessed 14 Jan. 2019.

“The effects of adenoidectomy and tonsillectomy on speech and nasal ….” Accessed 14 Jan. 2019.

“Effects of tonsillectomy on speech and voice. – Semantic Scholar.” Accessed 14 Jan. 2019.

“Fact Sheets – Speech Pathology Australia.” Accessed 14 Jan. 2019.

Additional Information

Speech Pathology Australia Fact Sheet: Speech sounds
Lisp: When /s/ and /z/ are hard to say
Speech Pathology Australia: Communication Milestones