Non-contact optical sensing of vocal fold paralysis using speckle pattern analysis

Vocal fold paralysis (VFP) is characterized by impaired vocal fold movement, commonly resulting from nerve damage during surgical procedures. Current diagnostic methods rely on endoscopic examinations requiring specialized physicians, reducing accessibility and potentially delaying treatment. We propose a non-contact optical sensing method using speckle pattern analysis for VFP identification. Our approach uses external laser illumination and a camera that captures speckle patterns, providing a non-invasive and real-time assessment. The technique uses spectral analysis enhanced by sliding window scanning to extract amplitude peaks across vocal fold regions. Our clinical measurements on 10 subjects (3 healthy and 7 VFP patients) demonstrate identical bilateral voice frequencies, but amplitude varies significantly according to the paralysis side. Healthy subjects presented amplitude ratios close to 1, while VFP patients showed distinct asymmetric patterns: ratios below 0.5 for right-sided paralysis and above 2 for left-sided paralysis, enabling effective VFP detection and localization with potential for clinical implementation.