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MLU stands for mean length of utterance. It’s a way to measure how complex a child’s language skills are. To find a child’s MLU, you count the number of morphemes (smallest units of meaning) in 100 of their utterances (phrases or sentences) and divide by 100. A higher MLU score means the child has more advanced language abilities.
At what age is MLU most useful?
MLU is most useful in assessing language development in children between the ages of 2 and 5 years old, as this is a critical period for language acquisition.
Can MLU be used to assess writing skills?
No, MLU is only used to assess spoken language. Other measures, such as mean length of written sentences (MLWS), can be used to assess writing skills.
How often should MLU be assessed?
The frequency of MLU assessments will depend on the individual child and their specific language development needs. Speech-language pathologists and other professionals can help determine the appropriate frequency of assessments based on the child’s progress and goals.
Can MLU be used to assess language development in languages other than English?
Yes, MLU can be adapted for assessing language development in various languages. While the specifics may differ, the underlying concept of measuring morpheme usage to gauge language complexity remains applicable across different languages.
Mean length of utterance (MLU) is used in child language acquisition research to calculate children’s productive vocabulary. It is computed by taking a sample of a child’s natural speech, counting the morphemes (individual words or parts of words that carry meaning), and dividing by the number of utterances.
MLU provides insight into a child’s language development:
For example: A typically developing 3-year-old may have an MLU around 3.0, using short sentences like “I want juice.” An MLU of 2.0 at that age could mean the child needs support building vocabulary and grammar skills.
| MLU Range | What It Means |
|---|---|
| 1.0 – 2.0 | Using mostly single words and some short phrases. |
| 3.0 – 4.0 | Combining 3-4 words into longer sentences. |
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