Percent Consonant Correct as an Outcome Measure for Cleft Speech in an Intervention Study

Percent consonant correct (PCC) was originally described by Shriberg and Kwiatkowski [J Speech Hear Disord. 1982 Aug;47(3):256-70] as a severity metric for phonological speech disorders, and has been adapted and used in many studies on speech sound disorders. It is well-recognized that cleft speech is complex, consisting of several interacting parameters assessed simultaneously, with error sounds not in the listener's own language. In speech outcome studies, narrow phonetic transcription and the reporting of intra- and inter-rater reliability are acknowledged as the gold standard. However, cleft speech brings special challenges to this task, as complex speech disorders are known to be associated with low transcriber agreement. Recent studies informed the decision to use PCC as the primary outcome measure in a cleft speech intervention study, given its common usage and familiarity. The aim was to specifically evaluate the intra- and inter-rater reliability of PCC in an intervention study, in contrast to other types of speech outcome studies.