Interdental vs. Lateral Lisp
Article by Montana Nuvoli (Certified Practising Speech Pathologist B.Ed, MSpPath)
Interdental vs. Lateral Lisp: What’s the Difference?
Lisps are a common speech error, but not all lisps are the same. Two types of lisps we see most commonly at QPAH are interdental lisps and lateral lisps – both are considered atypical articulation patterns, and each requires a different approach to speech therapy.
Interdental LispAn interdental lisp occurs when the tongue pushes between the front teeth during the production of /s/ and /z/ sounds, resulting in a “th”-like sound.
For example, “soup” may sound like “thoup” and “zebra” may sound like “thebra”.
Lateral LispA lateral lisp involves air escaping over the sides of the tongue, rather than through the centre of the mouth. This creates a “slushy” or “wet” sounding distortion, especially on /s/, /z/, and related sounds like /sh/ and /ch/.
Why Does it Matter?
Because interdental and lateral lisps are produced differently, they require different strategies during speech therapy. Interdental lisps often benefit from visual models and tongue placement cues (such as “keep the snake inside the cage!” exercises), while lateral lisps require more structured work to reshape airflow and tongue position.
When Should You Seek Support?
If you notice that you or your child consistently produces distorted /s/ or /z/ sounds, or if you or your child’s speech is difficult to understand, the team at QPAH is here to help. One of our experienced Speech Pathologists can conduct a full assessment and provide you with a targeted therapy plan.
Please feel free to reach out to our Southport or Varsity Lakes team via phone on 07 5647 6120 or email info@qpah.com.au today. You can find more information about our Speech Therapy services at QPAH here.
