Psychometric properties of the Intelligibility in Context Scale in monolingual Spanish-speaking children with and without speech sound disorders from Peru

Purpose: This study explored the construct validity, internal consistency, and criterion validity of The Intelligibility in Context Scale: Spanish (ICS-S) with monolingual Spanish-speakers from Peru. Method: Participants included 40 Spanish-speaking children (3 years and 3 months to 10 years and 11 months of age), n = 21 with typical speech, and n = 19 with speech sound disorders (SSD). Caregivers completed the ICS-S and children completed a single word articulation test; percent of consonants correct (PCC) were calculated. To evaluate construct validity, correlations were run between the ICS-S mean and the 7 ICS items; mean ICS-S scores in those with and without an SSD were compared using the Wilcoxon rank-sum test. Additionally, correlations were conducted between PCC and ICS-S mean scores to assess criterion validity and Chronbach's alpha was used to assess internal consistency. Because eight participants were rated as having both an SSD and severe hypernasality (defined as EAI=4), we ran sensitivity analyses with these participants excluded. Results: The mean ICS-S score for the children with SSD was 3.5 and for the children with typical speech was 4.4. Correlations between item and total mean on the ICS-S were significant (p = 0.000 - 0.004) in all but one case (parent's rating with the ICS-S mean score for the children with typical speech and those without CP; p = 0.203 & 0.131). Mean ICS-S scores were significantly lower in those with SSDs (p < 0.001). Criterion validity between PCC and the ICS-S mean score was r = 0.564, CI= 0.307 - 0.745 p < 0.001 and internal consistency between all the test items on the ICS-S was alpha = 0.913. Most results (except one) remained consistent when the eight with SSD and severe hypernasality were excluded. Conclusions: The ICS-S demonstrated construct and criterion validity as well as internal consistency for a cohort of monolingual Spanish children with and without SSD. These findings support the use of the ICS-S for screening for speech sound disorders (SSDs) in Spanish-speaking children.