Saturday, February 18, 2012

MLU: An overview

MLU is a term that is used when referring to a younger child (1-5 years old) and their language abilities. It stands for Mean Length of Utterance. Basically it is referring to the average number of words (or units of meaning) the child puts together during one speaking turn. As a general rule, one-year-olds should be using one word in each utterance or phrase, two year olds should be putting 2 words together, three year olds 3. Four-year-olds are getting real smart and should be putting about 6 words together.
Now, it's a little more complicated than at first glance because the child gets credit for units of meaning. For example, if the child says "balls" and adds an -s to indicate a plural, then that is a unit of meaning so they get two points for that. If they add an -ed and say "I walked there", that is 4 points because they use walk and add -ed to indicate past tense. Very clever, these children are! (see this link for a much more detailed overview).
I think it's GREAT information for parents of young kids so that you are able to listen to your child and evaluate this part of their language abilities. Maybe they'r a language prodigy and you didn't know it! Or maybe they're a little behind and you've been wondering.
My two year old boy happens to be somewhat of a genius child. Not to brag or anything, but his MLU is about 7. Here is a conversation he had (with himself) while playing with his trains:
"Hey look! Stop train! You cannot cross my bridge! Uh oh! Here comes another bridge! You better cross it! (Then his train track broke) Mom, you can help me do this? It's pretty hard to do. You can take me to the hospital? Okay this is the hospital. Thank you! He bonked his head. You help me take him to the doctor? I will. OK! Oh man. This is gonna be sweet!"

Isn't he great? Well some kids are just born with an easier ability to learn language. Some kids might be a little slower in picking up on it. If your child is 3 years old and they are still generally only using 1-2 words in each phrase, you might want to get them evaluated. And next time I'll post some suggestions on what you can do with younger kids to try to help them start expanding their utterances and putting more words together.

Did you like this post? Was it helpful? Do you have more questions? Let me know!


  1. This was great information! Thank you!

  2. I was really excited to laern this and raise my level of awareness

  3. Interesting. I like these posts. And I do have a question. Just because I'm curious. Can people do things to stifle their child's language skills? For example, there's a lot of hype about teaching toddlers sign language but it seems to me that teaching them a handful of signs actually prevents them from trying to vocalize. I have never seen a kid who speaks really well (would you call it a a high MLU?) who also uses sign language. It seems to me that if you were going to continue using A WHOLE LOT of sign language in your family then it would make sense to teach that toddler sign. Am I wrong?

    1. I know this is a really late response but I just saw this question but in case someone else has the same question, I will answer this. One could stifle a child's language development but mostly by not talking and interacting with the child, providing wrong language model (or not correcting wrong productions when they are no longer appropriate for the child's age) or by discouraging the child from talking for whatever reason. As long as the child interacts with someone however, they should be able to acquire language without serious difficulties (unless they have a language impairment). I believe the sign language you are referring to is "baby signs". These have become a hot topic in recent years and are mostly used for children starting from 6 months to 2 years. This is not full on sign language but rather limited number of individual signs for the most common things in a young child's life such as: more, drink, eat, mom, dad, play, etc. Research shows that baby signs do not slow down language acquisition in any way in fact children who use baby signs seem to acquire verbal language earlier. The main benefit of baby signs is that a child develops muscles that enable children to use these signs (or approximations) before he/she develops necessary articulation skills. A babies therefore can communicate before before they are able to speak. The signs prevent children from getting frustrated because parents don't understand what they need. It is important however for the parents to use the signs while saying the words when trying to communicate to the child. Even when a child makes a sign, it is a good idea for the parent to ask, you want "_____?" and make the sign while saying the word. That way the child not only makes a connection between the sign and the concept but also with the name. Eventually, when the child gets older, the parent can just say the word without using the sign. It's not that the sings will prevent them from using spoken language but rather provide a tool for them to express something when they don't have the skills to do so yet.