The following manuscript has just been published
McLeod, S., Harrison, L. J. &
McCormack, J. (2012). Intelligibility in Context Scale: Validity and reliability of a subjective rating measure. Journal of Speech, Language, and Hearing
Research, 55, 648-656.
Purpose:
To describe a new measure of functional intelligibility, the Intelligibility in
Context Scale (ICS), and evaluates its validity, reliability, and sensitivity
using clinical measures of severity of speech sound disorder: percentage of
phonemes correct (PPC), percentage of consonants correct (PCC), and 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 via the Diagnostic
Evaluation of Articulation and Phonology. Parents completed the 7-item ICS
questionnaire 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 (α=0.93), 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).
Conclusion:
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.
