Perceptual evaluation of hypernasality, audible nasal airflow and speech understandability using ordinal and visual analogue scaling and their relation with nasalance scores.

PURPOSE: Perceptual assessments remain the most commonly utilized procedure to diagnose and evaluate resonance disorders. However, the discussion continues about which rating scale has to be applied. Therefore, this study aimed to compare the reliability and validity of ordinal and visual analogue scales to rate hypernasality, audible nasal airflow and speech understandability.

METHODS: Four experienced speech-language pathologists rated 35 speech samples of children with a range of hypernasality, audible nasal airflow and speech understandability, using an ordinal scale and a visual analogue scale. Intraclass correlations coefficients determined intra- and inter-rater reliability. The model of best fit was determined by plotting both rating scales against each other. A Pearson correlation coefficient verified the relationship between both rating scales and nasalance scores determined by a Nasometer.

RESULTS: Good intra- and inter-rater reliability was found for both rating scales. A multiple regression analysis revealed a curvilinear relationship between both rating scales, indicating a slight preference to rate all parameters by a visual analogue scale. Comparable correlations with nasalance scores were found.

CONCLUSIONS: This study confirms that visual analogue scale ratings form a reliable and valid alternative for ordinal ratings in the perceptual judgments of hypernasality, audible nasal airflow and speech understandability. A combination of both rating scales may even combine the advantages and eliminate their limitations. However, further research is necessary to verify how this new approach can be implemented in available protocols for clinical practice, audits and research.