State-Space Approach to Structural Representation of Perturbed Pitch Period Sequences in Voice Signals

GABRIEL ALEJANDRO ALZAMENDI; GASTÓN SCHLOTTHAUER; MARÍA EUGENIA TORRES

JOURNAL OF VOICE : OFFICIAL JOURNAL OF THE VOICE FOUNDATION.

MOSBY-ELSEVIER

Año: 2015 vol. 29 p. 682 - 692

0892-1997

Objectives. The aim of this study is 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, while cycle estimates captured short-term, auto-regressive 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.