Scoping review of the Intelligibility in Context Scale

Speech intelligibility describes the degree of understanding messages between speakers and listeners. Speech intelligibility plays an important role in examining children’ speech, in diagnosing speech sound disorders, in setting goals, planning intervention, and evaluating effectiveness of speech interventions. The Intelligibility in Context Scale (ICS) is one of the most popular speech intelligibility measurement tools and has been translated into more than 60 languages across the world. This paper presents a scoping review of 39 publications including five describing, 19 norming and validation studies and 15 studies reporting on the use of ICS. Based on content analysis, this paper describes the development and translation, norming, validation and use of the ICS with children speaking English (five descriptions and nine papers), children speaking 14 other languages across the world (21 papers), and children speaking Vietnamese in Vietnam (four papers). Participants in the ICS studies were: monolingual, bilingual and multilingual; with and without speech sound disorders; and from 1-2 years old to adults but mainly in the preschool age range. The ICS’s mean scores, internal reliability, internal consistency, sensitivity, specificity as well as other psychometric properties were reported in ICS studies. These indicators reveal evidence that ICS is a reliable scale to use in research and clinical practice to measure speech intelligibility of children speaking different languages across the world including children speaking northern and southern Vietnamese dialects.