Aim: Stuttering is a communication disorder that involves both manifest speech disfluencies and associated symptoms. The purpose of the present study was to introduce an easily administered and ecologically valid assessment tool designed for perceptual evaluation of stuttered speech, FreDESS (frequency of stuttering events, duration of events, effort, secondary behaviours, and severity). More specifically, we wanted to study its reliability and validity.
Method: Video recordings of conversations with 38 people who stutter (PWS), 19 females and 19 males aged 13-25, were assessed by three speech language pathologists (SLP). Inter- and intrajudge reliability was estimated with intraclass correlation, standard error of measurement, and agreement between listeners. Internal consistency for the FreDESS parameters was estimated with Cronbach's alpha (α). To test the validity of FreDESS, the relationships between the average estimated parameters of frequency, duration, secondary behaviours, and severity of FreDESS and the Stuttering Severity Instrument (SSI-3), were analysed using intraclass correlation.
Results: The interjudge reliability was good, especially for the frequency, duration, and severity parameters (90 per cent + agreement given 1 scale point difference). All parameters of the FreDESS had strong intrajudge reliability (ICC = 0.86-0.94) and the overall internal consistency was high (α = 0.98). The average ratings on the two assessment scales were in line with each other (r = 0.90-0.96), indicating high concurrent validity.
Conclusion: The FreDESS scale for the assessment of stuttered speech may be a valuable tool in clinical and research contexts. It is a valid and more time-efficient assessment instrument than the more commonly used SSI.
Keywords: Stuttering; assessment scale; manifest stuttering symptoms; reliability; validity.