The intelligibility in Context Scale: validity and reliability of a subjective rating measure

• Published in: Journal of speech, language, and hearing research language, and hearing research, 2012-04, Vol.55 (2), p.648-656
• Main Authors: McLeod, Sharynne, Harrison, Linda J, McCormack, Jane
• Format: Article
• Language: English
• Subjects: Audiometry, Speech; Child; Child Language; Children & youth; Communication; Communication (Thought Transfer); Construct Validity; Disability Evaluation; Dysphonia - diagnosis; Environmental Influences; Factor Analysis; Faculty; Familiarity; Families & family life; Family (Sociological Unit); Female; Humans; Intelligibility; Male; Parents; Phonemes; Phonetic Transcription; Phonetics; Phonology; Predictive Validity; Preschool children; Ratings & rankings; Reproducibility of Results; Speech Intelligibility; Speech perception in children; Speech Production Measurement; Speech Skills; Speech Therapy - methods; Speech, Intelligibility of; Surveys and Questionnaires - standards; Validity
• ISSN: 1092-4388; 1558-9102
• DOI: 10.1044/1092-4388(2011/10-0130)

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). 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. 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 (α = .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). 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.