Speech sounds are like any other skill in communication development, they are learnt at different ages. Typically, vowel sounds develop first, followed by the consonant sounds.
Most children will develop the ability to move and speak in a predictable manner. However, every child is different, and this may vary, we use speech sound norms (information gathered about many children) to help us know when we might expect a typical child to make certain speech sounds.
The visual above represents the age at which 90% of children pronounce the speech sound correctly based on McCleod and Crowe (2018).
Example of the sounds: /zh/ – measure, /ng/ – ring , /th/ (voiced) – feather, /th/ (voiceless) – three
