Dealing with the unknown - addressing challenges in evaluating unintelligible speech.

When investigating the interaction between speech production and intelligibility, unintelligible speech portions are often of particular interest. Therefore, the fact that the standard quantification of speech production - the Percentage of Consonants Correct (PCC) - is only computed on intelligible speech is unsatisfying. Our purpose was to evaluate a new quantification of speech production: the Percentage of Intelligible and Correct Syllables (PICS) designed to address this limitation. A secondary purpose was to explore a task designed to elicit connected speech - concurrent commenting - offering more control of intended speech production compared to free conversation. Nine children with SSD participated in four speech elicitation tasks, varying with respect to ecological validity, and to degree of control: (1) word imitation, (2) picture naming, (3) concurrent commenting of a silent short video, and (4) free conversation. Speech accuracy was analysed in terms of PCC-Revised (PCC-R) and PICS, and intelligibility with regards to the Proportion of Intelligible Syllables (PINTS). A strong correlation was observed between PICS and PCC-R, supporting the construct validity of PICS. Further, a moderate correlation was seen between PICS and PINTS, presumably reflecting that these measures capture different - although related - constructs. No difference was seen between concurrent commenting and free conversation in terms of articulation proficiency or intelligibility; however, this needs further investigation based on more data. Nevertheless, we suggest concurrent commenting as a useful method for eliciting connected speech; in retaining more control over intended target words compared to free conversation, this task may be particularly useful in the context of unintelligible speech.