Listener Ratings of Stuttering: Evaluating Two Auditory-Perceptual Scales

Stuttering is a motor speech difference characterized by a disruption in the fluency, timing, and rhythm of speech. There is a lack of agreement on how to reliably and efficiently assess stuttering in research and the clinic. This study aims to compare the validity and reliability of two types of auditory-perceptual scales, direct magnitude estimation and equal-appearing interval scales, on assessing stuttering in adult speakers.

Two experiments compared unfamiliar listener ratings of speech samples from adults who stutter. Raters used one of two different rating scales to determine the construct validity and reliability of scaling procedures for capturing stuttering. The two experiments varied by the number and duration of samples (set number of syllables vs. set duration) and by the training given to participants (defining stuttering severity vs. allowing participants to define severity themselves).

Both experiments demonstrated the appropriateness of both scales for rating stuttering.

Contrary to earlier studies, our findings indicated that a 7-point equal-appearing interval scale validly captured unfamiliar listeners' perception of stuttering severity. Future study is needed to determine the number of raters needed to provide stable ratings as well as the utility of average or single ratings to capture clinically relevant change.