Lisps – Should you be worried?

Andrea Cooper
Senior Speech Pathologist

When I tell people that I am a speech pathologist, often the response is; “Oh so you work with people who have stutters and lisps”. Well as explained in my previous blogs, speech pathologists work in a variety of areas, not just stutters and lisps. But it is still an important topic that often needs further explanation. Lisps tend to be the most ‘well-known’ speech difficulty, but what exactly is a lisp?

What is a lisp?

A lisp is an articulation disorder. It occurs when a child is having difficulty producing the ‘s’ or ‘z’ sounds. Sometimes children with a lisp also have difficulty producing other related sounds such as ‘sh’ ‘ch’ and ‘j’.

There are two main types of lisps; an interdental lisp – This occurs when your tongue goes between your front teeth and makes a ‘th’- sound for the ‘s’ and ‘z’ sounds. Examples include saying ‘thun’ for ‘sun’ or ‘thoup’ for ‘soup’. This kind of lisp is considered a part of normal speech development and is typical for children before the age of 4.

The other type of lisp is called a lateral lisp. This is where the air escapes over the sides of the tongue instead of the front of the tongue. It makes the “s” sound ‘slushy’ and unclear.

This type of lisp is not usually seen in typical speech development. A child is less likely to ‘grow out of’ this kind of lisp, and will need therapy to help it resolve.

When should you seek advice from a speech pathologist?

Should we be working towards eliminating your child’s lisp? Drew Barrymore, Ita Buttrose, Jamie Oliver and Daffy Duck are just a few famous personalities that have lisps. So, should you be worried about your 4 year old?

There is mixed advice in the speech pathology profession as to when we should start working in ‘lisping’. Research conducted by Sanders in 1972 indicated that mastery of the ‘s’ and ‘z’ sounds occurred closer to 7-8 years of age. Whereas ‘The Goldman Fristoe Test of Articulation’ suggests that most children master the ‘s’ sound by 5 years of age (Goldman & Fristoe, 2000).
Some expert speech pathologists recommend that if the lisp persists beyond 4.5-5 years of age, intervention is warranted (Bowen, 2012).

Remember if your child has a lateral lisp we would always recommend you see a speech pathologist. However, when that pesky tongue is coming between those teeth for the ‘s’ sound, we need to consider the impact it is having on your child.

The ‘right’ age for therapy for one child may be different from the ‘right’ age for another, child even within the same family. A speech pathologist is able to determine the nature of a lisp, and whether or not it is appropriate for his/her age. They will also be able to work out if your child is ready for therapy as they need to have reasonably good listening, self-monitoring and attention skills for therapy to be successful. I generally suggest to parents that we have a try at intervention, and if we feel that they are not quite ready, we leave can wait a little bit longer.

Waiting well past 4 and a half years of age is not good advice. The longer the child waits before receiving therapy the stronger any ‘habit factor’ will be. My decision whether to work on a interdental lisp or not, is dependent upon many different factors such as the severity of the lisp, whether the child is being teased, whether they can cope with having their speech examined and corrected and whether the child can actually produce the “s” and “z” sounds correctly after modelling and prompting. Ultimately if a child is ready and motivated and the family are committed to doing the home practise, I believe the sooner therapy gets under way, the better.

Therapy is essential when a child’s lisp is impacting their confidence and if they are being bullied about their speech. It doesn’t matter how severe the lisp is if it is affecting a child’s emotional and mental health. For example a six year old boy has just started school and has a very minor lisp. As a result he is bullied mercilessly every day for an entire school term. He cries to his parents and looks for ways to stay at home. He has to change schools to escape the taunts.

Some people are not worried by a lisp, and that’s fine too. In the case of a mild lisp, it may hardly be noticeable at all, and their speech can be understood by both familiar and unfamiliar listeners.

If you are concerned about your child’s lisp, I would recommend seeing a speech pathologist for advice:

  • If your child has a lateral lisp (slushy ‘s’ sound)
  • If an interdental lisp is still evident when your child’s permanent front teeth are through.
  • If an interdental lisp is particularly severe and impacting on many speech sounds.
  • If your child has a lisp at around 4 and a half years of age.
  • If your child is self-conscious or embarrassed by their lisp.
  • If you are worried!

Happy talking!


Bowen, C. (2012). Lisping: When /s/ and /z/ are hard to say. Retrieved from Caroline Bowen Speech-Language Therapy on 10-1-2011.
Goldman, R. & Fristoe, M. (2000). Goldman-Fristoe Test of Articulation – Second Edition. Pearson Education.
Sander, E. K. (1972). When are speech sounds learned? Journal of Speech and Hearing Disorders, 37(1), 55–63.

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