Background: A review of the literature related to the use of multisyllabic words in the assessment of speech sound disorders (SSD) in children reveals the importance of using these words for providing additional information such as prognostic information. Despite strong literature in other languages, there is limited research on examining the production of these words in the Persian language among preschool children.

Aims: This study aims to design and assess the psychometric properties of a multisyllabic words test (MWT) for evaluating speech sound production skills in Iranian preschool children.

Method: One hundred and twenty children with typical development (60 males, 60 females), and 20 children with SSD (10 males, 10 females) whose parents signed an informed consent form participated in a cross-sectional study. Forty words were extracted from an item pool, including 532 multisyllabic words with 3, 4, 5, and 6 syllables. The content, face, construct, and differential validity of MWT were examined. For evaluating construct validity, the differences among six age groups, between males and females, and between control and SSD children were examined in terms of total score, percent consonants correct (PCC), percent vowels correct (PVC), and percent phonemes correct (PPC). Reliability (test-retest, and score-rescore) and internal consistency were determined using 20 children at a one-week interval, and interrater reliability was determined. Descriptive statistics, ANOVA, independent t-test, and Tuckey’s post hoc test were used for data analysis in SPSS software, version 26.

Results: In comparing the age groups, the results showed a significant difference in terms of total score, PCC and PPC (P<0.001), but no significant difference was found in PVC (P=0.23). No significant differences were found between males and females in total score, PCC, PPC, or PVC. In comparing control and SSD children, the results showed a significant difference between the two groups in total score, PCC, PPC (P<0.001), and PVC (P=0.02). The Intraclass correlation coefficient (ICC) was 0.98 for test-retest reliability and 0.79 for intra-rater reliability. The internal consistency was 0.75 for 3-syllable words, 0.65 for 4-syllable words, and 0.63 for 5-syllable words. 

Conclusions: The Persian MWT can be used as a valid and reliable instrument for measuring the speech production ability of Iranian children with SSD aged 4–7 years in clinical settings or for research. This test is consistent with other tests, such as the Polysyllable Preschool Test in terms of considering methodological principles such as inclusion words with different lengths, phonetic forms, and stress patterns, high imageability, using common words for preschool children, and providing opportunities for eliciting common error patterns of the target language.

Implications for children and families: Your child’s ability to produce multisyllabic (words of three or more syllables) is a significant milestone in their speech development. This skill lays the foundation for future literacy skills.

Implications for practitioners: The Persian multisyllabic word test is a reliable and valid instrument that could be utilised for evaluating speech production.

Key words: multisyllabic words, Persian, speech sound production, validity, reliability, test

This presentation relates to the following United Nations Sustainable Development Goals:

• SDG 3: Good Health and Well-being
• SDG 4: Quality Education