LinguiSystems Articulation Test–Normative Update (LAT-NU)
Authors: Linda Bowers, MA, CCC-SLP / Rosemary Huisingh, MA, CCC-SLP
The LinguiSystems Articulation Test–Normative Update (LAT-NU) was designed to identify children and young adults with abnormal articulation patterns. It ensures a thorough examination of all sounds and blends by presenting several sounds more than one time in the same position. All positions at the word level are tested.
The test allows examiners to rate the severity of the speech-sound disorder, rate the intelligibility of speech, and evaluate stimulability. The test also allows examiners to screen for childhood apraxia of speech (CAS), a neurological disorder that impairs the precision and consistency of speech.
New Features in the Normative Update
- Characteristics of the normative sample collected in 2008 (N = 3,011) were restratified by age relative to region, gender, race, and ethnicity and are the same as those reported for the preschool, school-age, and adult population reported in the ProQuest Statistical Abstract of the United States, 2017 (ProQuest, 2017).
- Each item on the test was reevaluated using both conventional item analyses to choose “good” items, and differential item analyses to find and eliminate potentially biased items.
- A major effort has been made to demonstrate conclusively that the normative update is both reliable and valid. The LAT-NU was subjected to diagnostic accuracy analyses, particularly rigorous techniques involving the computation of the sensitivity index, specificity index, and the receiver operating characteristic/area under the curve (ROC/AUC) statistic.
- Severity ratings that correspond to the Articulation Proficiency Score are now provided.
Administration and Scoring
The test provides a comprehensive Articulation Proficiency Score, which represents an individual’s overall speech sound ability. The Examiner Record Booklet provides space to record speech-sound errors by substitution, omission, or distortion.
The LAT-NU can be used to screen for CAS through the evaluation of the individual’s sequential productions of twelve multisyllabic words. Intelligibility and stimulability can also be assessed. Intelligibility of speech is rated by noting the type and frequency of errors in a picture description task. Stimulability is assessed immediately after an incorrect production is made, and determines if the individual is able to imitate a correct production.
The Examiner Record Booklet also provides a two-page summary that allows examiners to visually analyze the individual’s speech errors by word location, type, and stimulability. All phonemes tested in the LAT-NU are included in the Speech Sound Error Analysis section.The Examiner’s Manual discusses the test’s theoretical and research-based foundation, item development, standardization, administration and scoring procedures, normative tables, and guidelines for using the test’s results. Reliability and validity studies were conducted with typically developing students and students who had previously been diagnosed with an articulation disorder.
The average coefficient alpha is .92 for the Articulation Proficiency Score. New validity studies demonstrate the test’s ability to differentiate students with an articulation disorder from typically developing students. The results demonstrate that an Articulation Proficiency cutoff score of 94 resulted in a sensitivity of .77, a specificity of .85, and a receiver operating characteristic/area under the curve of .89.