author =      {Eric A. Lehmann and Anders M. Johansson},
  title =       {Dynamics Models for Acoustic Speaker Tracking---Preliminary Results},
  type =        {{NICTA/WATRI} Technical Report},
  number =      {PRJ-NICTA-PM-023},
  institution = {Western Australian Telecommunications Research Institute},
  address =     {Perth, Australia},
  month =       {August},
  year =        {2007},
  abstract =    {This report presents a study of various dynamics models (motion models) for an implementation in the frame of a particle filtering approach to acoustic speaker tracking. As a Bayesian filtering method, a particle filter relies on the definition of two main concepts, namely i) the measurement modality, and ii) the transition (dynamics) equation. Whereas a significant research effort has been devoted to improving the algorithm's performance by considering various types of observations (measurements), the influence of the dynamics formulation on the resulting tracking accuracy has received little attention so far. This work attempts to provide some insight into this secondary aspect of particle-filter design by considering several types of models, based on a Cartesian coordinates as well as polar coordinates definition of the state vector. A coarse calibration of the model parameters is carried out on the basis of real audio data recorded in a reverberant environment. The performance of the resulting particle filters is then assessed using extensive experimental simulations. An aspect of special interest considered in this work is related to the behaviour of the tracker during the silence gaps existing between utterances in the speech signal. This report demonstrates that the ability to achieve a reduced tracking error during periods of speech inactivity is influenced by both the chosen model as well as the specific tuning of its parameters.}