Comparison of intelligibility measures for children with velopharyngeal insufficiency: visual analog scale ratings, interval scales, and orthographic transcription (OT)-based measures.

Regardless of the underlying cause for speech impairment in speakers with cleft palate, a universal consequence of cleft palate is reduced speech intelligibility. Still, there is no standardised approach for measuring intelligibility for speakers with cleft speech. The current study aimed to determine the relationship between orthographic transcription (OT)-based measures, interval-scale ratings, and visual analog scale (VAS) ratings for perceptual judgements of intelligibility in speakers with cleft palate as judged by speech-language pathologists (SLPs). The speaker participants were six speakers with velopharyngeal insufficiency secondary to cleft palate. Four sets of sentences from the Hearing in Noise Test were recorded from each speaker. A total of 14 SLPs provided their intelligibility judgement on these speaker's recordings by word-by-word orthographic transcriptions, a visual analog scale (0-100), and a 5-point interval rating scale. A Spearman rank correlation test indicated a negative, strong correlation between OT-based measurements and VAS scores (r = -.94; p = 0.01) and between OT-based measurements and interval rating scores (r = -.77, p = 0.01). A strong, positive correlation was found between scores obtained from VAS and interval rating scales (r = .83, p = 0.05). The strong relationship between the objective measure of intelligibility (i.e. OT-based measure) and a subjective measure of intelligibility (i.e. VAS and interval scale) supports using a less time-consuming VAS as a substitute for orthographic transcription in measuring intelligibility in cleft palate speech.