Doctoral students Micah Hirsch and Austin Thompson were recently published in a special issue of Brain Sciences on dysarthria (a neurological speech disorder) assessment and intervention. Working with Drs. Kaitlin Lansford and Yunjung Kim, Hirsch and Thompson led and derived the project that focused on the “reliability and validity of speech-language pathologists’ (SLP) estimations of speech intelligibility in dysarthria.”

“This project is the result of a directed individual study that Austin and I completed with Dr. Lansford,” Hirsch said. “Austin and I have been working on this project for about a year. It has been an incredible experience working with Austin on this project, and it is really exciting to see that our work has finally been published.”

Speech intelligibility describes how well a speaker is understood by the listener. This is a common measure used in speech therapy services provided by SLPs. However, according to Hirsch and Thompson, little research has been done testing the reliability and validity of the subjective intelligibility ratings SLPs use for estimating speech intelligibility in dysarthria. The pair examined two subjective methods for measuring intelligibility, the visual analog scale (VAS) method and a percent estimation method commonly used in clinical settings. Their study found both the SLP percent estimations and VAS ratings of intelligibility to be reliable but could not recommend one more strongly than the other.

“This is because our results show that the average percent estimations or VAS ratings of intelligibility across several SLPs are reliable, but the ratings from individual SLPs are more variable and not as reliable,” Hirsch said. “Future research needs to consider the individual SLP characteristics that impact the reliability and validity of their intelligibility estimations and ratings for dysarthria.”

With the results from their current study, Thompson has one recommendation for SLPs: that the SLPs consistently use one method for rating intelligibility.

“The two methods for measuring speech intelligibility may appear similar,” Thompson said. “However, our study found that they may be measuring slightly different constructs.”

Looking forward to the future, Hirsch and Thompson plan to continue their research on this topic. Specifically, they will examine the individual SLP characteristics that affect the reliability and validity of their intelligibility ratings.

“We are planning to continue investigating the individual SLP characteristics. For example, we are interested in investigating how the years of work experience may affect the accuracy of an SLP’s intelligibility ratings or how these ratings may be affected by the type of work setting (i.e., medical vs. non-medical positions),” Hirsch said. “This will allow us to explain the variation between SLPs.”

Read Hirsch and Thompson’s published article here to learn more!