Phonological Mean Length of Utterance in 48-60-Month-old Persian-speaking Children with Isfahani Accent: Comparison of Story Generation and Conversation Samples

Objective:Phonological Mean Length of Utterance (PMLU), a quantitative measure for assessment of phonological skills, has been considered in developmental studies as a diagnostic and clinical criterion in phonological development. Moreover, it is an indicator rate of the efficacy of the intervention. The PMLU is a word level measure that can be calculated on the child’s transcribed speech sample (transcription). To calculate PMLU, all consonants and vowels of both the child’s produced words and target words (standard production of words in native adults) are individually scored. Proportion of Whole-Word Proximity (PWP), another phonological quantitative measure, includes ratio of the produced PMLU to targeted word PMLU. PWP indirectly reflects the intelligibility of speech. Since languages are distinctive in syllabic and phonological structures, PMLU should be studied as a language- specific measure. PMLU has been designed specifically to assess phonological skills in spontaneous speech. Spontaneous speech sampling methods are advantageous since they consider the effect of morphological and syntactic skills, length, and complexity of words, and they could show the normal development of the word complexity. This study was conducted to determine PMLU and PWP in 48 to 60 months old Persian-speaking children with Isfahani accent and to compare them in story generation and conversation sampling methods. The potential sensitivity of PMLU to growth was also examined. Method & Materials:This is an observational and cross-sectional study that was taken for one year in 2016 in Isfahan, Iran.100 children aged 48-60 month (51 boys and 49 girls) participated in story generation sampling and 67 children (32boys and 35 girls) participated in conversation sampling. The participants were selected from 261 kindergartens under the supervision of the Welfare Organization of Isfahan province using the convenience sampling method. After completing the consent form and considering inclusion criteria; conversation and story generation samples were collected. Audio samplings were done in the same room using the same software (Clear Record Lite-v2.1). Raters transcribed the first fifty words of the recorded speech samples.Finally, We used the formula to calculate Target PMLU and Child PMLU based on the normal production of an adult who speaks Persian with Isfahani accent and child’s productions,respectively. To evaluate Inter-rater reliability, raters randomly transcribed 20% of all samples to recalculate values. Participants’ story generation and conversation scores were entered into SPSS16 separately. Kolmogorov-Smirnov test was used to examine the data distribution. Based on the data distribution, paired t-test and Wilcoxon were used to compare measurements, and Pearson and Spearman were used to investigating the associations. Results:Child PMLU, Target PMLU, and PWP measures of story generation method were 8/794, 8/811, 0/998 and of conversation method were 9/068, 9/093, 0/998, respectively. Correlation test results showed significant relationship between age and PWP in story generation (r=0/308) and conversation (r=0/313)Comparing child PMLU in story generation and conversation showed a significant relationship between child PMLU in both sampling methods (P = 0/000). Result of the Target PMLU comparison in two methods of story generation and conversation (P =0/000) was significant. PWP did not show a significant difference between the two sampling methods (P = 0/973). Inter-rater reliability was calculated at 0.70 Conclusion:The average PMLU values in Persian were higher than similar studies which could be related to the unique characteristics of Persian language and Isfahani accent. The lack of a significant relationship in story generation and conversation PWP could possibly indicate that PWP was not affected by the sampling method, while differences in sampling methods can affect PMLU values. Results of the study showed an association between ageand PWP. This study can be used as a basis for quantitative studies in the field of children’s phonological assessment using the Persian whole words. However, the longitude studies in different age groups with a high level of evidence in this field can convince therapists to use whole word measures in clinics.