Perceptual Judgments of Resonance, Nasal Airflow, Understandability, and Acceptability in Speakers with Cleft Palate: Ordinal versus Visual Analogue Scaling

Abstract

Objective To investigate the reliability of ordinal versus visual analogue scaling (VAS) ratings for perceptual judgments of nasal resonance, nasal airflow, understandability, and acceptability in speakers with cleft palate. Design Within-subjects comparative study. Setting Multisite. Participants Five specialist speech and language therapists from U.K. Regional Cleft Centres. Outcome Measures Participants rated 30 audio speech samples obtained from the Speech and Language Therapy archives of Great Ormond Street Hospital. They rated the identified speech parameters using each scaling method, with 1 month between rating tasks. The model of best fit was determined to examine validity, and both intra- and inter-rater reliability were also computed. Results VAS ratings were valid for all parameters when plotted against ordinal ratings, and the model of best fit revealed only a slightly stronger curvilinear than linear relationship between the scaling methods. Intra-rater reliability was high for both rating methods across all six speech parameters. There was also high inter-rater reliability for both ordinal and VAS ratings of hypernasality, nasal emission, nasal turbulence, understandability, and acceptability, and for the ordinal ratings of hyponasality. Conclusions Perceptual judgments of nasal resonance, nasal airflow, understandability, and acceptability were similar using VAS and ordinal scaling, indicating that both scaling methods were appropriate for measuring the cleft speech parameters. VAS, however, may offer statistical advantages, and there is a growing body of evidence advocating its use for the measurement of prothetic speech parameters.