Calculating the Mean Length of Utterance (MLU) is an essential skill for understanding language development. It is a measure used to quantify the linguistic complexity of a speaker, particularly in children, by computing the average number of morphemes per utterance. In this article, we will discuss how to calculate MLU, its relevance, and its applications.

1. Understanding Morphemes

Before calculating MLU, it is crucial to understand what morphemes are. A morpheme is the smallest unit of meaning in a language, which can be a single word or a unit within a word that carries meaning. For example, ‘cat’ is one morpheme, while ‘cats’ contains two morphemes: ‘cat’ + ‘s.’

2. Collecting Data

To calculate MLU effectively, collect a reliable data sample from spontaneous speech. Typically, 50-200 utterances from a child’s speech are considered sufficient for MLU computation; however, obtaining more data will result in more reliable results.

3. Counting Morphemes

The next step is identifying and counting morphemes in collected data. Pay attention to inflections (such as plural or past tense), compounds (i.e., ‘butterfly’), and contractions (e.g., “isn’t”). Each unit should be counted as a separate morpheme.

Some examples:

– “Dogs play” contains three morphemes: “dog” + “s” + “play.”

– “Running” contains two morphemes: “run” + “ning.”

4. Calculating MLU

Once you have obtained the total number of morphemes in your dataset:

– Divide the total number of identified morphemes by the total number of utterances.

– The quotient obtained represents the MLU for that dataset

For example:

If you have collected 75 utterances containing a total of 220 morphemes:

– MLU = 220 morphemes / 75 utterances

– MLU = 2.93

This means that on average, the child’s utterances contain approximately 2.93 morphemes.

5. Interpreting MLU

MLU is an essential aspect of assessing language development in children. Generally, a higher MLU indicates more complex language use and better linguistic skills.

It is essential to compare MLU results with norms available for children of the same age range. This evaluation will allow you to identify typical patterns or potential language delays that could warrant further investigation.

6. Applications of MLU

– Assessing language development in children

– Identifying language delays and disorders

– Tracking language progress over time

– Evaluating intervention programs for their effectiveness

– Research purposes

In conclusion, understanding how to calculate the Mean Length of Utterance (MLU) is a vital skill when examining an individual’s linguistic abilities. By following these steps and understanding how to interpret the results, you can assess speech and language developments effectively, identify concerns early on, and evaluate their progress over time.