Model-based classification of nonstationary vocal fold vibrations

• Published in: The Journal of the Acoustical Society of America Vol. 120; no. 2; pp. 1012 - 1027
• Main Authors: Wurzbacher, Tobias, Schwarz, Raphael, Döllinger, Michael, Hoppe, Ulrich, Eysholdt, Ulrich, Lohscheller, Jörg
• Format: Journal Article
• Language: English
• Published: Woodbury, NY Acoustical Society of America 01.08.2006; American Institute of Physics
• Subjects: Adult; Audition; Biological and medical sciences; Case-Control Studies; Diagnosis; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Mathematical Computing; Measures; Models, Biological; Perception; Phonation; Phonation - physiology; Phonation Structures; Pitch; Pitch Discrimination - physiology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Speech Pathology; Time Factors; Vertebrates: nervous system and sense organs; Vibration; Vocal Cords - physiology; Voice Disorders; Voice Disorders - physiopathology; Vocal tract; Measurement; Vibration; Non stationary condition; Vocal cord; Phonation; Real time; Modeling; Steady state; Optimization; Stationary condition; Biomechanics; Hearing; Asymmetry; Classification; Speech articulation disorder; Pitch(acoustics)
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.2211550

Classification of vocal fold vibrations is an essential task of the objective assessment of voice disorders. For historical reasons, the conventional clinical examination of vocal fold vibrations is done during stationary, sustained phonation. However, the conclusions drawn from a stationary phonation are restricted to the observed steady-state vocal fold vibrations and cannot be generalized to voice mechanisms during running speech. This study addresses the approach of classifying real-time recordings of vocal fold oscillations during a nonstationary phonation paradigm in the form of a pitch raise. The classification is based on asymmetry measures derived from a time-dependent biomechanical two-mass model of the vocal folds which is adapted to observed vocal fold motion curves with an optimization procedure. After verification of the algorithm performance the method was applied to clinical problems. Recordings of ten subjects with normal voice and ten dysphonic subjects have been evaluated during stationary as well as nonstationary phonation. In the case of nonstationary phonation the model-based classification into “normal” and “dysphonic” succeeds in all cases, while it fails in the case of sustained phonation. The nonstationary vocal fold vibrations contain additional information about vocal fold irregularities, which are needed for an objective interpretation and classification of voice disorders.