Quantifying unintelligible speech

Evaluations for children with speech sound disorders (SSDs) are pretty standard across the board. We take a speech sample through imitated words, picture naming, and/or free conversation. We measure which consonants they produce correctly vs. incorrectly, do an oral mech exam, and call it a day. But when children have long stretches of unintelligible speech, things can get complicated. How can we analyze speech if we have no idea what the child is saying? Öster et al. attempts to help us quantify unintelligible speech using a measure called percentage of intelligible correct syllables (PICS).  


SLPs measured intelligible correct syllables by listening to a short sample of connected speech in children ages 4–10 with SSD (approximately 100 words). Since syllables are still evident in unintelligible speech, the SLPs were able to measure the number of accurate syllables divided by the total number of syllables in the sample to obtain the percentage of correct syllables. Furthermore, children’s’ PICS scores were correlated with their percentage of correct consonants (PCC) showing us that PICS can be used as a valid measure for assessing speech sounds. For those tricky children who are unintelligible more often than not, PICS could provide a baseline from which to measure progress.  

These researchers also used a novel method for collecting a connected speech sample. Using concurrent commenting, children watched a silent video, typically a clip from a children’s TV episode, and were instructed to describe the ongoing events of the video to a listener. This procedure allows SLPs to gain a sample of narration, which usually contains more linguistically complex and longer utterances compared to conversational speech. The video also provides contextual clues for the SLP to use when transcribing the sample.

Ready to jump in? Check out the article for even more details on how to assess a child using PICS and concurrent commenting. Both are handy tools to consider using when assessing highly unintelligible children.


Öster, C.A.M., Ode, C., & Strömbergsson, S. (2019). Dealing with the unknown—addressing challenges in evaluating unintelligible speech. Clinical Linguistics and Phonetics. doi:10.1080/02699206.2019.1622787.