Intelligibility in Context Scale: Internal Consistency and Validity

Nida Şanlı Merve Evci
Abstract

The basis of verbal communication is the correct understanding of the speaker's intention by the listener. Intelligibility depends on speaker's age, gender, language/dialect, speech sound disorder, communicative competencies; listener's proximity to the speaker, listener's language/dialect, and communicative competence; task and context. Intelligibility is a product of those interrelated domains. Any breakdowns in these processes or domains bring problems related to intelligibility. Considering language and speech disorders, intelligibility problems are inevitable. Focusing on the dynamic interrelated components that affect intelligibility, it is necessary to look at it from a holistic perspective. World Health Organization (WHO) proposed The International Classification of Health and Functioning (ICF) classification that provides a holistic conceptual framework. ICF emphasizes the need to evaluate the severity of the individual's speech disorder as well as the impact of this condition on the individual's life (activity and participation) and contextual factors. Purpose: The Intelligibility in Context Scale (ICS) is a scale that evaluates intelligibility in terms of environmental factors expressed in the ICF. This scale has been translated into Turkish, but no study has been done on its validity and reliability. In this study, the aim was to study the internal consistency and validity of the ICS scale. Method: The study included 26 preschool children with speech sound disorders and their parents. Parents completed the ICS scale. Child participants were administered articulation-phonology test- articulation subtest (SST-SET) and they were divided into groups as mild, moderate, severe and very severe according to their ICS scores. Spontaneous speech was recorded from children and percentage of consonant correct (PCC) was calculated. According to the PCC scores, the participants were divided into 4 groups as mild, mild-moderate, moderate and severe. Normalization of the data was evaluated with the Shapiro Wilk test. The correlation between SST-SET, PCC scores and ICS-PCC scores was analyzed by Spearman correlation analysis; the correlation between SST-SET and ICS scores was evaluated with Pearson correlation analysis. The difference between the ICS scores of the SST-SET severity groups was analyzed with Kruskal Wallis, and the difference between the groups was analyzed with the Mann Whitney U test. The difference between PCC severity groups ICS scores was analyzed by ANOVA, and the difference between group pairs were analyzed with Bonferroni correction. ICS internal consistency was calculated with Cronbach’s alpha coefficient. Results: It was found that the correlation between SST-SET and PCC was significant, positive and high (r= 0.924; p<0.001); correlation between PCC-ICS was significant, positive and high (r= 0.962; p<0.001); SST-SET and ICS was significant, positive and high (r= 0.885; p<.001). There was a significant difference on the ICS scores of the SST-SET groups (p=0.001). This difference was due to the significant difference between all group pairs (p<0.05). A significant difference was found between the ICS scores of the PCC severity groups (p=0.00). There was a statistically significant difference between mild vs. mildly moderate (p=<0.05), mild vs. moderate (p<0.001), mild vs. severe (p<0.001), mildly moderate vs. moderate (p=<0.05), mildly moderate vs. severe (p<0.001) groups. CA coefficient was calculated as 0.957 which indicates excellent internal consistency. Conclusion: The Turkish version of ICS is a valid tool with excellent internal consistency that can be used to define/assess intelligibility in Turkish literature. 


Keywords

intelligibility, speech sound disorders, the intelligibility in context scale, ICF, speech and language evaluation.


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