title: State-Space Approach to Structural Representation of Perturbed Pitch Period Sequences in Voice Signals.
abstract: OBJECTIVE
  The aim of this study was to propose a state space-based approach to model perturbed pitch period sequences (PPSs), extracted from real sustained vowels, combining the principal features of disturbed real PPSs with structural analysis of stochastic time series and state space methods.
  
  
  METHODS
  The PPSs were obtained from a database composed of 53 healthy subjects. State space models were developed taking into account different structures and complexity levels. PPS features such as trend, cycle, and irregular structures were considered. Model parameters were calculated using optimization procedures. For each PPS, state estimates were obtained combining the developed models and diffuse initialization with filtering and smoothing methods. Statistical tests were applied to objectively evaluate the performance of this method.
  
  
  RESULTS
  Statistical tests demonstrated that the proposed approach correctly represented more than the 75% of the database with a significance value of 0.05. In the analysis, structural estimates suitably characterized the dynamics of the PPSs. Trend estimates proved to properly represent slow long-term dynamics, whereas cycle estimates captured short-term autoregressive dependencies.
  
  
  CONCLUSIONS
  The present study demonstrated that the proposed approach is suitable for representing and analyzing real perturbed PPSs, also allowing to extract further information related to the phonation process.
authors.affiliation: Laboratorio de Señales y Dinámicas no Lineales, Facultad de Ingeniería de la Universidad Nacional de Entre Ríos and Consejo Nacional de Investigaciones Científicas y Técnicas, Entre Ríos, Argentina.
authors.forename: Gabriel A
authors.initials: GA
authors.lastname: Alzamendi
authors.affiliation: Laboratorio de Señales y Dinámicas no Lineales, Facultad de Ingeniería de la Universidad Nacional de Entre Ríos and Consejo Nacional de Investigaciones Científicas y Técnicas, Entre Ríos, Argentina. Electronic address: gschlotthauer@conicet.gov.ar.
authors.forename: Gastón
authors.initials: G
authors.lastname: Schlotthauer
authors.affiliation: Laboratorio de Señales y Dinámicas no Lineales, Facultad de Ingeniería de la Universidad Nacional de Entre Ríos and Consejo Nacional de Investigaciones Científicas y Técnicas, Entre Ríos, Argentina.
authors.forename: María E
authors.initials: ME
authors.lastname: Torres
mesh_terms: D006801:Humans; D008962:Models, Theoretical; D013061:Speech Acoustics
keywords: Jitter; Perturbed pitch periods; State-space models; Stochastic pitch model; Structural time-series analysis