articulation and phonological disorders

What is “normal” and what is the difference between the two?

• Children may say some sounds the wrong way as they learn to talk. They learn some sounds earlier, like p, m, or w. Other sounds take longer to learn, like z, v, or th. Most children can say almost all speech sounds correctly by 4 years old. A child who does not say sounds by the expected ages may have a speech sound disorder. You may hear the terms "articulation disorder" and "phonological disorder" to describe speech sound disorders like this.

• An ARTICULATION disorder occurs when specific sounds are produced in error with a substitution, omission, addition, and distortion. These errors are motor-based and are at the phonetic level, where your jaw, tongue, lips, teeth, and palate are working to alter the air stream released from your vocal folds. For example, substituting the “s” sound for a “th” sound, “yes” —> “yeth”. When a child cannot produce age-expected sounds, it decreases their intelligibility and takes away from their message.

• A PHONOLOGICAL disorder occurs when the child has difficulty organizing the sound patterns for adult speech within their brain. For example, a phonological process called fronting is when back sounds /k/ and /g/ that are produced by the tongue moving up in the back, are replaced with FRONT sounds /t/ and /d/ which are made by the tongue coming up in the front (tat/cat, doat/goat, etc). These errors are at the phonemic level.