The intelligibility in context scale: validity and reliability of a subjective rating measure

Sharynne McLeod*, Linda J. Harrison, Jane McCormack

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

152 Citations (Scopus)


Purpose: To describe a new measure of functional intelligibility, the Intelligibility in Context Scale (ICS), and evaluate its validity, reliability, and sensitivity using 3 clinical measures of severity of speech sound disorder: (a) percentage of phonemes correct (PPC), (b) percentage of consonants correct (PCC), and (c) percentage of vowels correct (PVC). Method: Speech skills of 120 preschool children (109 with parent-/teacher-identified concern about how they talked and made speech sounds and 11 with no identified concern) were assessed with the Diagnostic Evaluation of Articulation and Phonology (Dodd, Hua, Crosbie, Holm, & Ozanne, 2002). Parents completed the 7-item ICS, which rates the degree to which children's speech is understood by different communication partners (parents, immediate family, extended family, friends, acquaintances, teachers, and strangers) on a 5-point scale. Results: Parents' ratings showed that most children were always (5) or usually (4) understood by parents, immediate family, and teachers, but only sometimes (3) by strangers. Factor analysis confirmed the internal consistency of the ICS items; therefore, ratings were averaged to form an overall intelligibility score. The ICS had high internal reliability (a =.93), sensitivity, and construct validity. Criterion validity was established through significant correlations between the ICS and PPC (r = .54), PCC (r = .54), and PVC (r = .36). Conclusions: The ICS is a promising new measure of functional intelligibility. These data provide initial support for the ICS as an easily administered, valid, and reliable estimate of preschool children's intelligibility when speaking with people of varying levels of familiarity and authority.

Original languageEnglish
Pages (from-to)648-656
Number of pages9
JournalJournal of Speech, Language, and Hearing Research
Issue number2
Publication statusPublished - Apr 2012
Externally publishedYes


  • speech sound disorder
  • intelligibility
  • assessment
  • International Classification of Functioning
  • Disability and Health (ICF-CY)
  • children


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