Analytical validation of digital measure of intelligibility in progressive supranuclear palsy.

INTRODUCTION

Progressive supranuclear palsy (PSP) causes progressive speech impairment. Digital speech analysis can objectively and remotely quantify measures like intelligibility, typically judged subjectively by experts during clinical visits. The objective of this study is to validate digital intelligibility measurement in PSP via BioDigit Speech (BioSensics LLC, United States).

METHODS

Forty-nine PSP patients performed standardized passage-reading scored by BioDigit Speech and three experts (18 + years of experience); expert mean score (EMS) served as the reference standard.

RESULTS

Digital intelligibility showed high correlation and agreement with EMS (r = 0.90, ICC = 0.84 in native speakers), while systematically scoring below EMS. Moreover, the digital measure discriminated PSP clinical severity as well as or better than EMS, particularly for PSP-QoL-11 with a steeper standardized response. Correlations of digital measure with the clinical scales were moderate (up to -0.51), significant (p-values <0.02) and consistently higher than the ones of EMS. Raters appeared to use top-down information to recover underlying messages, resulting in saturated scores near 1.0 and low-to-moderate inter-rater agreement.

CONCLUSION

Collected remotely with minimal burden, digital speech measures like intelligibility may serve as objective, sensitive outcomes for communication-focused interventions and PSP trials.