Mean length utterance refers to increasing a child’s sentence length. MLU is calculated by the smallest unit of language known as a morpheme. This means that if you were to dissect a word into its different parts, each part would have its own meaning. An example of this would be the word “apple”. This is known as one morpheme as you cannot derive any more meaning from the word. You cannot divide “ap” and “ple” and have different meanings. However, if you have the word “apples” you can divide the word into “apple” and “s” because apple represents a singular object whereas apples has the meaning of more than one.
MLU is based on Brown’s Stages of Language Development. This provides the developmental norms for children starting at 12 months of age.
During structured play given visual/verbal cues, student will use 2 word utterances 80% of the time for a 15 minute session.
Hierarchical Cuing Systems
The first way to increase MLU is to increase vocabulary. The goal is to have the child have at least 50 words in their vocabulary. These words should include nouns, verbs, descriptors, possessives (“my”), negatives (“no”), demonstratives (“that”), and question words (“what”).
After improving vocabulary, it is important to improve use of grammatical markers. For example, a child who says “I want some cookies please” would receive credit for 6 morphemes but a child who says “want cookies please” only receives three.
Finally, once the vocabulary and grammatical markers are improved, the child can work on expanding their sentences. This can be done through playing or a structured activity. By simply providing models, the child can begin to expand their MLU.
Activity Breakdown
MLU is traditionally targeted in early intervention and therefore most therapy is play based. This can include playing with kitchen toys and asking for “more apple, eat food, drink water, etc” in order for the child to indicate their wants and needs. This can also be used during play activities including cars, coloring, sensory bins, or any other play activity. The goal is to model for the child in order to elicit language. If the child is targeting 2 word utterances, the clinician’s goal is to also model 2 word utterances.
Data collection can be used through a language sample. During a designed activity, the clinician will record 50 utterances and later go back to determine how many morphemes were produced during those utterances.
Evidence Based Research
The mean length utterance that a child produces is a valuable estimate to early language acquisition (Rice et al., 2010). Measuring languages through utterances is a great marker for language impairments. This benchmark assesses individuals differences and developmental changes in grammatical development during early stages of language. Portratz and colleagues reported that "MLU is a responsive and valid measure of children's syntactic development across age and discourse context during early school-age years" (Portratz et al., 2022)
References
Grammar resource page. Speech And Language Kids. (2022, May 31). Retrieved December 2, 2022, from https://www.speechandlanguagekids.com/grammar-resource-page/
Increasing sentence length (MLU). Speech And Language Kids. (2022, May 25). Retrieved December 2, 2022, from https://www.speechandlanguagekids.com/increasing-sentence-length-mlu/
Potratz, J. R., Gildersleeve-Neumann, C., & Redford, M. A. (2022). Measurement properties of mean length of utterance in school-age children. Language, Speech, and Hearing Services in Schools, 53(4), 1088–1100. https://doi.org/10.1044/2022_lshss-21-00115
Rice, M. L., Smolik, F., Perpich, D., Thompson, T., Rytting, N., & Blossom, M. (2010). Mean length of utterance levels in 6-month intervals for children 3 to 9 years with and without language impairments. Journal of Speech, Language, and Hearing Research, 53(2), 333–349. https://doi.org/10.1044/1092-4388(2009/08-0183)