Children start learning speech sounds from the moment they're born! Sweet cries of WAAAAH or contented sounds, ooh, are actually developmental milestones that you should keep track of and are ways that a child may communicate to parents or caregivers. Making noises and sounds are essentially linguistic cross training to developing more advanced speech sounds; speech sounds leads to stringing sounds together to form words and sentences.
In Early Start, one of the most frequently asked questions is whether or not a child should receive speech therapy because some of the sounds aren't present; other varying reasons why parents feel a child should receive speech are that the child's speech is unclear, the child replaces some sounds with others ("wabbit" for "rabbit," or "lellow" for "yellow"), or the child drops beginning or ending sounds in words ("how" for "house" or "top" for "stop").
Children under three years of age typically receive speech therapy because they are showing deficits in functional communication (i.e., basic communication skills to communicate needs and wants via gestures, words, or sentences). A child may receive speech therapy if she has less than five words at 20 months of age or is not putting two-word sentences together by 28 months.
Speech, like any other area of development, requires practice; therefore, errors will happen. Because of this, professionals typically start to assess articulation or speech sound acquisition after the age of three. Intelligibility (i.e., clarity of message) is often used to determine whether or not a child would be a good candidate for therapy. Flipsen's (2006) conversational intelligibility guideline is converted by dividing the child's age in years by four and converting the number into a percentage.
1 year—1/4 = 25% intelligible
2 years—2/4 = 50% intelligible
3 years—3/4 = 75% intelligible
4 years—4/4 = 100% intelligible
If you search the internet, I promise you that you'll find many varying charts of what is considered "normal" for speech sound production. Here is a developmental speech sound acquisition chart for children up to seven years of age. If you would like to download this chart, click here for the full high-resolution chart.
Flipsen, P. (2006). Measuring the intelligibility of conversational speech in children. Clinical Linguistics and Phonetics, 20, 202-312.
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