Phonetic intelligibility testing in dysarthria. Validity and reliability of listeners' perceptions

Speech intelligibility is a key concept in the clinical management of dysarthric speakers and demands assessment procedures which are reliable, valid and practicable at the same time. TFF—a Danish rhyme test—has been constructed in order to consider all three aspects. This article describes the considerations which underlie the construction of TFF and the empirical evaluation of the assessment. The evaluation focused on a) the validity of the assessment and b) the consistency of the listeners' perceptions. The results lead to the following conclusions: using rhyme tests as TFF may yield valid and reliable quantitative measures of intelligibility, though the applicability as qualitative instruments of analysis is highly questionable.