Speech Sounds

What are speech sounds?

Articulation is the way we produce speech sounds. We use our tongue, lips, teeth, jaw and vocal folds to produce speech sounds. Children can experience a range of difficulties that will affect the way they produce their speech sounds.

Most children will make mistakes with their speech sound production at some point in their development. Different sounds are expected to develop at different ages. A speech sound delay exists when a child continues to make mistakes with a particular sound or group of sounds past the age expected.

Speech sound delays involve articulation errors (making the sound) and phonological process errors (sound patterns). A phonological delay will cause patterns of speech sound errors.

What is speech intelligibility?

Speech Intelligibility refers to how well words can be understood
by an unfamiliar listener (stranger e.g. a shop assistant). There is a broad range of normal, but typically a child at

  • 19 – 24 months of age is 25% to 50% intelligible

  • 2 – 3 years the child is 50% to 75% intelligible

  • 3 – 4 years the child is 80% intelligible

  • 4 – 5 years the child is 90% to 100% intelligible

What are the symptoms of an articulation delay?

Some of the most common symptoms of an articulation delay include the following:

  • Not sounding clear

  • Speech sounds slushy

  • Substituting one sound for another sound

What are the symptoms of a phonological delay?

  • Not sounding clear

  • Leaving off sounds at the beginning, middle and end of words

  • Changing sounds in words or in conversations

  • Substituting sounds in words

What are the causes of expressive language difficulties?

Often the causes of expressive language difficulties are unknown and a number of factors may be working together to contribute to your child’s difficulties. Family history is often the most likely indicator, although this may not always be the case. A child may have learnt to a produce a sound incorrectly, or may not have learnt the rules of speech sound production on their own. This may mean the child has a speech sound difficulty, and may not simply outgrow it.

Children who have experienced frequent ear infections with hearing loss are at risk of experiencing a speech sound difficulty.

Children who can say a sound when they copy an adult but don’t do it when talking in conversation, are not being lazy. This can often occur and may indicate the child is experiencing a phonological delay.


What is language delay?

language delay occurs when a child’s language is developing slower than other children of the same age, but it is following the typical pattern of development. For example, a child may be 4 years of age, but understanding and/or using language typical of a child who may be only 2.5 years of age. 

Children with language delays, typically present with the following:

  • Are late talkers

  • Have limited vocabulary development

  • Find it difficult to express themselves

  • Do not understand well or experience difficulty following directions