Validation of the Intelligibility in Context Scale for Jamaican Creole-Speaking Preschoolers

To describe validation of the Intelligibility in Context Scale (ICS; McLeod, Harrison, & McCormack, 2012a) and ICS-Jamaican Creole (ICS-JC; McLeod, Harrison, & McCormack, 2012b) in a sample of typically developing 3- to 6-year-old Jamaicans.

One-hundred and forty-five preschooler-parent dyads participated in the study. Parents completed the 7-item ICS (n = 145) and ICS-JC (n = 98) to rate children's speech intelligibility (5-point scale) across communication partners (parents, immediate family, extended family, friends, acquaintances, strangers). Preschoolers completed the Diagnostic Evaluation of Articulation and Phonology (DEAP; Dodd, Hua, Crosbie, Holm, & Ozanne, 2006) in English and Jamaican Creole to establish speech-sound competency. For this sample, we examined validity and reliability (interrater, test-rest, internal consistency) evidence using measures of speech-sound production: (a) percentage of consonants correct, (b) percentage of vowels correct, and (c) percentage of phonemes correct.

ICS and ICS-JC ratings showed preschoolers were always (5) to usually (4) understood across communication partners (ICS, M = 4.43; ICS-JC, M = 4.50). Both tools demonstrated excellent internal consistency (α = .91), high interrater, and test-retest reliability. Significant correlations between the two tools and between each measure and language-specific percentage of consonants correct, percentage of vowels correct, and percentage of phonemes correct provided criterion-validity evidence. A positive correlation between the ICS and age further strengthened validity evidence for that measure.

Both tools show promising evidence of reliability and validity in describing functional speech intelligibility for this group of typically developing Jamaican preschoolers.