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The Intelligibility in Context Scale in Tamil—Reliability and Validity Measures

Prianka Evangeline F., Deepali Nahata, Jasmine Lydia S.



Objective: The Intelligibility in Context Scale (ICS) was originally developed by Sharynne McLeod, Linda J. Harrison and Jane McCormack in 2012. It is a 7 item parent-rated questionnaire designed to assess speech intelligibility in very young children using a quantitative score out of 5. It is intended to supplement other clinical measures of speech intelligibility in providing a comprehensive picture of the speech of children with several speech impairments (speech sound disorders and childhood apraxia of speech). The ICS considers the various people with who children communicate with (parents, immediate family, extended family, friends, acquaintances, teachers and strangers), the environmental contexts of everyday communication, and the subsequent impact on children’s intelligibility. Therefore the ICS was constructed by taking account of the contextual factors outlined in the International Classification of Functioning, Disability and Health: Children and Youth Version (ICF‐CY, World Health Organization [WHO], 2007). The ICS has been translated to 28 languages including 3 Indian languages (Gujarati, Hindi and Punjabi). The purpose of this study is to adapt the ICS to the Tamil language for clinical use to rate Tamil speaking children’s functional speech intelligibility. The objectives of this study were to: a) translate and adapt the ICS to Tamil (ICS–T) b) obtain normative data for the ICS–T for Tamil speaking children c) measure the reliability (internal consistency and test-retest reliability) and validity (content validity, construct validity, and criterion validity) of the ICS–T. Methodology: The ICS–T was formulated by carrying out the official WHO four-step process of translation and adaptation of research instruments, which includes: forward translation, expert panel back-translation, pre-testing and cognitive interviewing, and the final version. The official WHO process was used to achieve the Tamil language version of the ICS that will be equally natural, acceptable, and can practically perform in the same way as the original. It was then administered on 280 typically developing children between three to six years of age whose first language was Tamil. To meet the description of typically developing, all participants demonstrated: (a) binaural hearing at 20 dB for 1 kHz, 2 kHz, and 4 kHz; (b) parent-reported absence of current or history of neurological concerns or pervasive developmental disorders. The children were selected from government-aided schools within Chennai, Tamil Nadu and were divided into three age groups with one-year intervals (3.0–4.0, 4.1–5.0, 5.1–6. 0) to obtain normative data for the ICS–T. The reliability measures of internal consistency were computed using Cronbach’s Alpha. Criterion validity was measured by comparing scores of ICS–T with other established and valid measures of speech severity: percentage of phonemes correct (PPC), percentage of consonants correct (PCC) and percentage of vowels correct (PVC) as determined by the Test of Articulation in Tamil (TAT) and the subjective rating measure of Speech Intelligibility Rating (SIR). Results: Mean ICS–T scores of typically developing Tamil speaking children between the ages of 3 and 6 were 4.7 with an SD of 0.3. The internal consistency of the ICS–T was 0.82. The scores on ICS–T positively correlate with PPC (p <0.01), PCC (p < 0.01) and PVC (p < 0.01).


Keywords: Intelligibility in context scale (ICS), percentage of phonemes corrects (PPC), percentage of consonants corrects (PCC), percentage of vowels corrects (PVC), speech impairments, speech intelligibility rating (SIR), test of articulation in Tamil (TAT).

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Prianka Evangeline F., Deepali Nahata, Jasmine Lydia S. The Intelligibility in Context Scale in Tamil—Reliability and Validity Measures. Research & Reviews: Journal of Medical Science and Technology. 2019; 8(3): 16–21p.

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