Model-based classification of nonstationary vocal fold vibrations

Abstract

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.

Investigating acoustic correlates of human vocal fold vibratory phase asymmetry through modeling and laryngeal high-speed videoendoscopy

“…The model proposed by Steinecke and Herzel (1995) has been repeatedly used to study asymmetric behavior during phonation Wurzbacher et al, 2006;Zhang et al, 2006) and whose behavior has been validated by more complex models that use Navier-Stokes flow solvers (Tao et al, 2007;Xue et al, 2010). Although alternative representations, such as the body-cover model (Story and Titze, 1995), may offer an enhanced feature set, they do not provide simple control over left-right vibratory asymmetry and have not been consistently applied to study asymmetric vocal fold vibration.…”

Model-based quantification of pathological voice production

“…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. Recently, high-speed recordings of non-stationary vocal fold oscillations were successfully classified with a time-dependent one-dimensional model [131].…”

Computation of physiological human vocal fold parameters by mathematical optimization of a biomechanical model

“…The lower bound 75% for j is on the basis of results of Wurzbacher et al 28 The upper bound 0.2 for U is defined in accordance with the relative endoscopic HS image processing error. 28 …”

“…28 The optimization parameter Q p mainly influences the oscillation amplitude. 30 An appropriate value of the initial optimization parameterQ p yields smaller amplitude differences between the curves c i,s [n] to be fitted and the model generated curves c M i;s n ½ ; where n ¼ 1,…, N denotes the frame number.…”

“…In recent attempts using the two-mass-models (2MM) 7,28,29 and the 2DM 20,30 only 1D trajectories at one or more specific locations on the vocal fold edges along the longitudinal direction were fitted. Classification schemes between healthy and pathological vocal fold vibrations were presented.…”