What causes a lisp?
The root of the issue involves muscle patterns and control. The tongue is a collection of muscles, even though we don’t typically think about it like that. The way we habitually use our muscles sets up a motor pattern. Think about another motor activity, such as a golf swing or running. Sometimes we learn a motor pattern that isn’t the best way to achieve the results we want. We may have to work with a golf pro or a physical therapist to learn how to retrain those muscles. That’s exactly what the child with a lisp needs to do. A speech-language pathologist can help the child learn how to control the tongue so that it stays where it needs to be (for example, behind the teeth).
Children’s motor patterns are more flexible when they are younger, so the earlier you can start shaping these motor habits, the better. Around age seven, kids’ motor patterns become more solidified, making it harder to change4. Therefore, learning a new motor skill as an adult can be harder than learning it as a young child. In addition, years of speaking with an incorrect tongue placement reinforce the incorrect motor habit. For example, if you practice a skill wrong 1,000 times a day, after a year or two, that’s a lot of practice with the wrong motor pattern! So the earlier we can help a child learn how to make the right sound, the better.
A Brief Description Of How We Produce Speech
Before diving into how speech therapy can treat a lisp, we first need to discuss how we produce the different sounds involved in speech. Three main features determine sounds:
1. Where we put our tongue/lips/jaw.
Is the tongue touching the roof of the mouth (like for the ‘l’ sound) or flat on the bottom of the mouth (like for the ‘ah’ sound)? Does the tongue come through the teeth (like for the ‘th’ sound) or stay behind the teeth (like for the ‘s’ sound)?
2. How the air flows.
Some sounds, like ‘t’ and ‘k’ stop the air completely and then have a little burst of air upon realease whereas other sounds like ‘s’ and ‘v’ have continuously-flowing air through a narrow opening. Some sounds come out of the nose. For example, ‘n’ and ‘m’ allow sound to come out of your nose which is why they sound different when you have a stuffy nose that blocks that sound from escaping.
What are the types of lisps?
Now that we’ve covered how we make sounds, we will focus specifically on lisps. There are two kinds of lisps: a frontal (or interdental) lisp and a lateral lisp. The frontal lisp (listen here) is what many people think of when they consider a lisp: the tongue extends through the teeth when it should stay behind the teeth to make the ‘s’ and ‘z’ sounds. The frontal lisp sounds like the ‘th’ sound. The second kind of lisp, the lateral lisp (listen here), occurs when the air escapes out of the sides of your tongue rather than in a forward trajectory straight down the middle of your tongue.
What does an interdental lisp sound like?
What does a lateral lisp sound like?
When is a lisp a problem?
A frontal lisp is developmentally appropriate until age 4-5, when ‘s’ and ‘z should be developed1. Do not worry if your toddler has a frontal lisp pattern; many kids grow out of it on their own. However, a lateral lisp is not found within typical English development, so therapy should be sought early. Fun fact: a lateral lisp is a correct speech sound in Welsh, so if your child speaks Welsh, there is no need to correct it.
Things that are associated with frontal lisps
A few things are commonly associated with frontal lisps, so it’s something to keep an eye on. A child with a lisp may have some (or none) of these.
How to fix a lisp
Working with a speech-language pathologist is the best way to help treat and cure a lisp. But here are three general tips:
- Use a mirror to create awareness of the tongue. Young children don’t have the same awareness of their bodies as adults. A mirror can provide some visual feedback so they can see when their tongue is protruding through their teeth.
- Use visual imagery. In addition to making it more like pretend play, using a metaphor such as “keep the tiger in the cage” (see here for a picture you can show your child) can help the child envision what they’re supposed to be doing with their tongue (in the case of a frontal lisp).
- Model a similar sound. Sometimes we can show the child a similar sound to help them channel the airflow correctly. For example, for a lateral lisp, speech-language pathologists will sometimes have them use a “long T” because the ‘t’ sound at the beginning can help get the airflow down the middle instead over the sides of the tongue (sounding like “tssss”).
If none of these tips work, your child may need to work with a speech-language pathologist to help get that motor pattern right and learn how to use the correct motor pattern all the time.
Lisps are one of the most common speech problems during childhood. As a speech-language pathologist, I have had countless interactions with people who said they went to speech as a child for their ‘s’ sounds but now produce it correctly. With the right speech therapy and practice, your child can become one of those “I used to have a lisp” success stories.
1McLeod, S., & Crowe, K. (2018). Children’s consonant acquisition in 27 languages: A cross-linguistic review. American Journal of Speech-Language Pathology, 27(4), 1546-1571.
2 Varadan, M., Chopra, A., Sanghavi, A. D., Sivaraman, K., & Gupta, K. (2019). Etiology and clinical recommendations to manage the complications following lingual frenectomy: A critical review. Journal of Stomatology, Oral and Maxillofacial Surgery, 120(6), 549-553.
3 Thompson, L. (2006). The association between frontal lisping and an anterior open bite, a tongue thrust swallow, the concurrence of an anterior open bite and a tongue thrust swallow, and slow diadochokinetic rate (Master’s thesis, University of Cape Town).
4Smith, A., & Zelaznik, H. N. (2004). Development of functional synergies for speech motor coordination in childhood and adolescence. Developmental Psychobiology, 45(1), 22-33.
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