Noise reduction for flows using nonlinear constraints
  On the basis of a local-projective with nonlinear constraints (LPNC) approach (see K. Urbanowicz, J.A. Holyst, T. Stemler and H. Benner, Acta Phys. Pol B 35 (9), 2175, 2004) we develop a method of noise reduction in time series that makes use of constraints appearing due to the continuous character of flows. As opposed to local-projective methods in our method we do not need to determine the Jacobi matrix.   The approach has been successfully applied for separating a signal from noise in the Lorenz model and in noisy experimental data obtained from an electronic Chua circuit. The method was then applied for filtering noise in human voice. 
Krzysztof Urbanowicz and Janusz A. Holyst