Speech disorders refer to problems in communication and related areas such as oral motor function. These delays and disorders can be sound substitutions and or sound distortions.

When a child has a simple lisp (producing [th] instead of [s], like "thing" instead of "sing" or "yeth" instead of "yes"), substitutes [w] for [l] or [r], or other similar errors, she is demonstrating an articulation disorder. Articulation refers to the manner in which a child produces a sound and the placement of the tongue, lips, and teeth. Common articulation errors are those listed above, in addition to [f] for [th] ("fum" for "thumb"), [l] for [y] ("lelo" for "yellow"). Many articulation errors are developmental in nature; that is, some sounds are later developing, and many children will produce these sounds incorrectly until they mature. One example is the [th] sound, as in "thumb". This is one of the latest sounds to develop (between the ages of 6 and 8). Therefore, if a 7-year-old can not yet say this sound, it is not reason to be concerned. Articulation errors do not significantly reduce the child's ability to be understood. The most common error sounds are [s] [l] and [r]. Some school therapists will not treat children with these errors until they are 6 or 7; however, if a child shows that he can be stimulated for these sounds, therapy can be successful when children are younger.