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; which can be addressed through speech therapy.